narcolepsy genetics


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(Updated 7/01/06)

[Research published prior to 1990 has been excluded.]

Lin L, Hungs M, Mignot E.
Narcolepsy and the HLA region.
J Neuroimmunol. 2001 Jul 2;117(1-2):9-20.
"Narcolepsy was first shown to be tightly associated with HLA-DR2 and DQ1 in 1983, suggesting a possible autoimmune mechanism. Early investigations failed to demonstrate this hypothesis, postulating that HLA-DR2 was only a linkage marker for another, unknown narcolepsy-causing gene. The autoimmune hypothesis is now being re-evaluated under the light of recent results. Like many other autoimmune disorders, narcolepsy usually starts during adolescence, is human leukocyte antigen (HLA)-associated, multigenic and environmentally influenced. Furthermore, HLA-association studies indicated a primary HLA-DQ effect with complex HLA class II allele interactions and a partial contribution of HLA to overall genetic susceptibility. Finally, recent result suggests that human narcolepsy is associated with the destruction of a small number of hypothalamic neurons containing the peptide hypocretins (orexins). This data is consistent with an immune destruction of hypocretin-containing cells as the most common etiology for human narcolepsy." [Abstract]

Siebold C, Hansen BE, Wyer JR, Harlos K, Esnouf RE, Svejgaard A, Bell JI, Strominger JL, Jones EY, Fugger L
Crystal structure of HLA-DQ0602 that protects against type 1 diabetes and confers strong susceptibility to narcolepsy.
Proc Natl Acad Sci U S A. 2004 Feb 17;101(7):1999-2004.
The MHC class II molecule DQ0602 confers strong susceptibility to narcolepsy but dominant protection against type 1 diabetes. The crystal structure of DQ0602 reveals the molecular features underlying these contrasting genetic properties. Structural comparisons to homologous DQ molecules with differential disease associations highlight a previously unrecognized interplay between the volume of the P6 pocket and the specificity of the P9 pocket, which implies that presentation of an expanded peptide repertoire is critical for dominant protection against type 1 diabetes. In narcolepsy, the volume of the P4 pocket appears central to the susceptibility, suggesting that the presentation of a specific peptide population plays a major role. [Abstract] [Full Text]

Krahn LE, Pankratz VS, Oliver L, Boeve BF, Silber MH.
Hypocretin (orexin) levels in cerebrospinal fluid of patients with narcolepsy: relationship to cataplexy and HLA DQB1*0602 status.
Sleep. 2002 Nov 1;25(7):733-6.
"STUDY OBJECTIVES: Hypocretin (orexin) deficiency (< 40 pg/ml) is highly associated with narcolepsy with cataplexy (89.5%) and more specifically with patients with cataplexy who are HLA DQB1*0602 positive (95.7%). The relationship between hypocretin-1 levels and narcolepsy without cataplexy or the DQB1*0602 allele is less clear. METHODS/DESIGN: This study compared cerebrospinal (CSF) hypocretin-1 in 13 patients with HLA DQB1*0602 allele and cataplexy to 4 HLA negative patients with cataplexy, 3 HLA positive patients without cataplexy, and 6 HLA negative patients without cataplexy, plus 15 neurologic controls. SETTING: Data were collected at a sleep disorders center. PATIENTS/PARTICIPANTS: Twenty-six patients with narcolepsy, with and without HLA DQB1*0602 and with and without cataplexy, as well as 15 neurologic controls. INTERVENTIONS: N/A. MEASUREMENT & RESULTS: Using analysis of variance techniques, statistically significant differences were found between the CSF hypocretin-1 levels in HLA positive patients and all other groups (P < 0.01). Although the sample size was small, subjects with the DQB1*0602 allele without cataplexy had lower hypocretin-1 levels than did other groups (other than the HLA and cataplexy positive group). Hypocretin-1 levels were not associated with age at diagnosis, age at lumbar puncture, body mass index at time of diagnosis, or body mass index at time of lumbar puncture. CONCLUSION: This data confirms the previous finding that undetectable hypocretin-1 levels are highly specific for HLA positive narcolepsy with cataplexy. The data suggests that the pathophysiology and, by extension, etiology of this disorder are distinctly different from the other conditions studied. The relationship of the DQB1*0602 allele and reduced hypocretin-1 levels needs further study." [Abstract]

Dolenc-Grosel L, Vodusek DB.
The importance of HLA DQB1*0602 typing in Slovene patients with narcolepsy.
Cell Mol Biol Lett. 2002;7(2):359-60.
"The HLA class II region genes DQB1*0602 and DQA1*0102 are currently the best genetic predictors for narcolepsy in humans (1(. The aim of this study was to identify the HLA DQ alleles (DQB1*0602 and DQA1*0102) in Slovene sporadic narcoleptic patients. 11 patients who fulfilled ICSD criteria for narcolepsy entered the study. DRB1*1501 DQB1*0602 was present in all the patients while DQA1*0102 was absent in 2 patients. We propose that DQB1*0602 typing is important in diagnosing narcolepsy in Slovene patients." [Abstract]

Hong SC, Leen-Kim, Park SA, Han JH, Lee SP, Lin L, Okun M, Nishino S, Mignot E.
HLA and hypocretin studies in Korean patients with narcolepsy.
Sleep. 2002 Jun 15;25(4):440-4.
"STUDY OBJECTIVES: Very few studies have evaluated narcolepsy in Asian countries, outside of Japan. Our goal was to study narcolepsy at the genetic, clinical and pathophysiological level in Korea. DESIGN: Prospective study of consecutive patients and age matched controls. Clinical data ascertained from the Stanford Sleep Inventory, Polysomnography and MSLT data, as well as clinical notes. High resolution DRB1 and DQB1 typing in all subjects and studies of CSF hypocretin-1 was also evaluated in a subset of patients. PARTICIPANTS AND SETTING: 20 patients diagnosed at St. Vincent and Korea University Hospitals (Seoul, Korea). 21 Korean control subjects. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: For narcoleptic subjects, mean age was 28.2 years old and 45% were female. Mean BMI was 23.9+/-3.4 kg/m2, a significantly higher value than that expected in an age- and sex-matched sample (p<0.01). All patients had sleepiness and cataplexy while the prevalence of other symptoms ranged from 60-75%. All but 2 subjects were HLA-DR15 (DR2), DQB1*0602 positive (90%). This high DQB1*0602 percentage compared with 24% DQB1*0602 positivity in 21 control Koreans. Protective effects were observed for the DQB1*0601 and DRB1*0406 alleles, Hypocretin (orexin) CSF studies were also performed in 6 cataplectic subjects, all of which had undetectable CSF hypocretin levels. Two of these subjects had started narcolepsy less than 1 year before analysis yet had undetectable hypocretin levels. CONCLUSION: These results illustrate the similarity of narcolepsy-cataplexy in Korea in comparisons with other more studied populations. We also identified a new potential HLA protective subtype, HLA-DRB1*0406." [Abstract]

Mignot E, Lin L, Rogers W, Honda Y, Qiu X, Lin X, Okun M, Hohjoh H, Miki T, Hsu S, Leffell M, Grumet F, Fernandez-Vina M, Honda M, Risch N.
Complex HLA-DR and -DQ interactions confer risk of narcolepsy-cataplexy in three ethnic groups.
Am J Hum Genet. 2001 Mar;68(3):686-99. Epub 2001 Feb 13.
"Human narcolepsy-cataplexy, a sleep disorder associated with a centrally mediated hypocretin (orexin) deficiency, is tightly associated with HLA-DQB1*0602. Few studies have investigated the influence that additional HLA class II alleles have on susceptibility to this disease. In this work, 1,087 control subjects and 420 narcoleptic subjects with cataplexy, from three ethnic groups, were HLA typed, and the effects of HLA-DRB1, -DQA1, and -DQB1 were analyzed. As reported elsewhere, almost all narcoleptic subjects were positive for both HLA-DQA1*0102 and -DQB1*0602. A strong predisposing effect was observed in DQB1*0602 homozygotes, across all ethnic groups. Relative risks for narcolepsy were next calculated for heterozygous DQB1*0602/other HLA class II allelic combinations. Nine HLA class II alleles carried in trans with DQB1*0602 were found to influence disease predisposition. Significantly higher relative risks were observed for heterozygote combinations including DQB1*0301, DQA1*06, DRB1*04, DRB1*08, DRB1*11, and DRB1*12. Three alleles-DQB1*0601, DQB1*0501, and DQA1*01 (non-DQA1*0102)-were found to be protective. The genetic contribution of HLA-DQ to narcolepsy susceptibility was also estimated by use of lambda statistics. Results indicate that complex HLA-DR and -DQ interactions contribute to the genetic predisposition to human narcolepsy but that additional susceptibility loci are also most likely involved. Together with the recent hypocretin discoveries, these findings are consistent with an immunologically mediated destruction of hypocretin-containing cells in human narcolepsy-cataplexy." [Abstract]

Kwon OJ, Peled N, Miller K, Pillar G, Peled R, Lavie P, Brautbar C, Amar A.
HLA class II analysis in Jewish Israeli narcoleptic patients.
Hum Immunol. 1995 Dec;44(4):199-202.
"HLA class II was investigated in eight Jewish narcoleptic patients, representing the total of such patients known in Israel at present, and in three patients suffering from sleep disturbances other than narcolepsy. All (11 out of 11) patients carried the serologic specificities DR2, DQ6 (DQ1). At the DNA level, all narcoleptics were found to be DRB1*1501, DQA1*0102, DQB1*0602 which indicates that the susceptibility gene may be located within the HLA class II region, DR, and/or DQ. As for the nonnarcoleptic patients with idiopathic hypersomnia, they carried different alleles of DR2 and DQ6, namely DRB1*1502, DQA1*0103, DQB1*0601. This study confirms that the incidence of narcolepsy in Israel is extremely low and that HLA class II genes or a gene(s) tightly linked to them are involved in the disease." [Abstract]

Okun ML, Lin L, Pelin Z, Hong S, Mignot E.
Clinical aspects of narcolepsy-cataplexy across ethnic groups.
Sleep. 2002 Feb 1;25(1):27-35.
"STUDY OBJECTIVES: The objectives of this study were to compare severity and clinical presentation for narcolepsy-cataplexy across various ethnic groups. A large sample of narcoleptic patients was also used to further describe symptomatology and natural history for this sleep disorder. DESIGN: Retrospective review of clinical data ascertained from the Stanford Sleep Inventory, polysomnography and MSLT data, as well as clinical notes. Ethnicity was narrowly defined as African (Black) Americans, Caucasians, Asians, and Latinos when both parents and the subject identified with a given ethnic group. SETTING: N/A. PARTICIPANTS: We compared the severity and clinical presentation of narcolepsy in 64 African Americans, 353 Caucasians, 32 Asians, 26 Latinos, and 9 subjects of mixed ethnicity. Subjects were recruited through the Stanford center for narcolepsy research. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: A striking similarity in symptomatology, age of onset, and disease severity was found across ethnic groups. Mean age of onset for sleepiness, hypnagogic hallucinations, sleep paralysis and cataplexy were 19.20, 19.50, 20.11 and 23.02 years old. We also found that narcoleptic patients have slightly but significantly elevated body mass index relative to normative data (106.6% of matched controls, p<0.005) and are born slightly more frequently during the month of March. A tight correlation between our previously validated cataplexy scale and DQB1*0602 positivity was observed. Two thirds of patients reported having cataplexy with laughing, 92% of those being DQB1*0602 positive independent of ethnicity. CONCLUSIONS: These results confirm the similarities in clinical presentation and natural history of narcolepsy-cataplexy in a large number of patients of various ethnic groups and cultural backgrounds." [Abstract]

Mignot E, Kimura A, Lattermann A, Lin X, Yasunaga S, Mueller-Eckhardt G, Rattazzi C, Lin L, Guilleminault C, Grumet FC, Mayer G, Dement WC, Underhill P.
Extensive HLA class II studies in 58 non-DRB1*15 (DR2) narcoleptic patients with cataplexy.
Tissue Antigens. 1997 Apr;49(4):329-41.
"Narcolepsy is a sleep disorder that has been shown to be tightly associated with HLA DR15 (DR2). In this study, 58 non-DR15 patients with narcolepsy-cataplexy were typed at the HLA DRB1, DQA1 and DQB1 loci. Subjects included both sporadic cases and narcoleptic probands from multiplex families. Additional markers studied in the class II region were the promoters of the DQA1 and DQB1 genes, two CA repeat polymorphisms (DQCAR and DQCARII) located between the DQA1 and DQB1 genes, three CA repeat markers (G51152, T16CAR and G411624R) located between DQB1 and DQB3 and polymorphisms at the DQB2 locus. Twenty-one (36%) of these 58 non-DR15 narcoleptic patients were DQA1*0102 and DQB1*0602, a DQ1 subtype normally associated with DRB1*15 in DR2-positive narcoleptic subjects. Additional microsatellite and DQA1 promoter diversity was found in some of these non-DR15 but DQB1*0602-positive haplotypes but the known allele specific codons of DQA1*0102 and DQB1*0602 were maintained in all 21 cases. The 37 non-DQA1*0102/DQB1*0602 subjects did not share any particular HLA DR or DQ alleles. We conclude that HLA DQA1*0102 and DQB1*0602 are the most likely primary candidate susceptibility genes for narcolepsy in the HLA class II region." [Abstract]

Hayduk R, Flodman P, Spence MA, Erman MK, Mitler MM.
HLA haplotypes, polysomnography, and pedigrees in a case series of patients with narcolepsy.
Sleep. 1997 Oct;20(10):850-7.
"An ongoing study of the genetics of narcolepsy ascertains families through a case series of narcoleptic probands using diagnostic criteria consisting of 1) clinical history of excessive somnolence, 2) a mean sleep latency on the multiple sleep latency test (MSLT) of less than 7.9 minutes, 3) the rapid eye movement (REM) sleep-related symptom of cataplexy, 4) nocturnal polysomnography ruling out sleep apnea syndrome, and 5) two or more transitions to REM sleep on the MSLT. All probands and first-degree relatives received clinical and laboratory evaluations as well as human leukocyte antigen (HLA) typing. Demographic characteristics of the 32 probands are as follows: 17 males and 15 females; mean age was 42.1 years (range 13-70 years). The polysomnographic data confirmed daytime sleepiness and increased tendency for REM sleep for the 32 probands. Nocturnal polysomnographic results are as follows: sleep latency, 3.2 minutes; total sleep time, 442 minutes. MSLT results are as follows: sleep latency, 3.1 minutes; REM latency, 6.9 minutes; number of REM periods, 3.2. HLA typing revealed the presence of the HLA haplotypes, DRB1*15 and DQB1*0602, in 21 narcoleptic probands, with two African-Americans having the DQB1*0602 but not the DRB1*15 allele. Among the 57 relatives of the 32 probands, 1/31 females and 7/26 males were found to be affected with narcolepsy (p < 0.02), which suggests a higher diagnostic rate in male relatives. The 21 probands who were positive for the DRB1*15 and DQB1*0602 haplotypes did not differ from the 10 probands who were negative for these alleles in terms of their nocturnal sleep parameters, MSLT findings, or clinical presentation. Three families with multiple individuals affected with narcolepsy are presented. Two families have more than one affected individual who does not have the high-risk HLA haplotype. In one of these families, the disease is segregating independently of any HLA haplotype. In the third family, there is cosegregation with HLA DRB1*15 and DQB1*0602. One family contains a pair of DNA-confirmed, monozygotic twins with narcolepsy who are discordant for cataplexy and have the HLA DR14(Dw9)/DQB1*0503 and DR4(Dw4)/DQB1*0302 haplotypes." [Abstract]

Dauvilliers Y, Bazin M, Ondze B, Bera O, Bazin M, Besset A, Billiard M.
Severity of narcolepsy among French of different ethnic origins (south of France and Martinique).
Sleep. 2002 Feb 1;25(1):50-5.
"STUDY OBJECTIVES: The aim of the study was to describe the clinical and polygraphical characteristics of narcoleptics, with and without cataplexy and to assess HLA predisposition across two different ethnic populations. DESIGN AND SETTING: Patients were 126 men and 58 women referred to the Montpellier Sleep Disorders Center (Mtp) and 12 men and 8 women referred to the Fort-de-France Sleep Disorders Center (FdF) (Martinique, a French West Indy island) with symptoms of narcolepsy. PARTICIPANTS: Narcoleptics were included if they had both excessive daytime sleepiness and clear-cut cataplexy (for the group with cataplexy), a mean sleep latency of less than 8 minutes and at least two sleep onset REM periods. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Narcolepsy without clear-cut cataplexy was rare (12/172) in the Mtp population whereas it was as frequent as full-blown narcolepsy (10/10) in the FdF population. Comparison between narcoleptics with cataplexy from the Mtp and FdF populations revealed a younger age of onset, a trend towards more severe sleepiness and lower frequency of cataplexy in Martinicans. Comparison between narcoleptics without cataplexy from the Mtp and FdF population revealed a higher frequency of hypnagogic hallucinations and sleep paralysis and a trend towards more severe sleepiness in Martinicans. 4.2% of the Mtp and 15% of the FdF patients were negative for HLA DR2. However all of them were positive for HLA DQ1. Moreover, a tight association with HLA DRB1*1503 was observed in Martinicans in contrast with DRB1*1501 in the Mtp population. Association with HLA DQB1*0602 was observed in 99.4% of narcoleptics with cataplexy and in 89.5% of those without cataplexy. CONCLUSIONS: Narcolepsy is a heterogeneous clinical syndrome, the more so as ethnic origins are considered. A modulating effect of HLA and non-HLA genes on symptoms disease may explain these differences." [Abstract]

Mignot E, Lin X, Arrigoni J, Macaubas C, Olive F, Hallmayer J, Underhill P, Guilleminault C, Dement WC, Grumet FC.
DQB1*0602 and DQA1*0102 (DQ1) are better markers than DR2 for narcolepsy in Caucasian and black Americans.
Sleep. 1994 Dec;17(8 Suppl):S60-7.
"In the present study, we tested 19 Caucasian and 28 Black American narcoleptics for the presence of the human leucocyte antigen (HLA) DQB1*0602 and DQA1*0102 (DQ1) genes using a specific polymerase chain reaction (PCR)-oligotyping technique. A similar technique was also used to identify DRB1*1501 and DRB1*1503 (DR2). Results indicate that all but one Caucasian patient (previously identified) were DRB1*1501 (DR2) and DQB1*0602/DQA1*102 (DQ1) positive. In Black Americans, however, DRB1*1501 (DR2) was a poor marker for narcolepsy. Only 75% of patients were DR2 positive, most of them being DRB1*1503, but not DRB1*1501 positive. DQB1*0602 was found in all but one Black narcoleptic patient. The clinical and polygraphic results for this patient were typical, thus confirming the existence of a rare, but genuine form of DQB1*0602 negative narcolepsy. These results demonstrate that DQB1*0602/DQA1*0102 is the best marker for narcolepsy across all ethnic groups." [Abstract]

Reutens DC, Haddad AP, Cantwell L, Berkovic SF.
HLA-DR2 negative narcolepsy in Australian Caucasians: clinical features, serology and sequence specific oligonucleotide typing.
J Neurol Sci. 1992 Nov;113(1):26-30.
"An almost invariable association with HLA-DR2 and DQw1 has previously been reported in Japanese and caucasian narcoleptics. We performed HLA typing in 18 Australian narcoleptics using serological techniques and sequence specific oligonucleotide probes. HLA-DQw1 was present in 15 patients and DR2 in 12; 3 patients with cataplectic narcolepsy were DR2-negative. The serological haplotype most strongly associated with narcolepsy was DRw15 (a subtype of DR2), DQw1. DRw15-positive patients were positive for the alleles DRB1*1501 and DQB1*0602 defined with oligonucleotide probes. We conclude that the association of narcolepsy with DR2 and DQw1 is not as strong as previously reported and the absence of DR2 or DQw1 does not preclude the diagnosis of classical narcolepsy, at least in caucasians. Secondly, DR2-positive narcoleptics possess characteristic serological subtypes and alleles defined with oligonucleotide probes that are also found in normals. Thirdly, the occurrence of DR2-negative cataplectic narcoleptics points to the existence of more than one narcolepsy susceptibility gene." [Abstract]

Mignot E, Lin X, Kalil J, George C, Singh S, Billiard M, Montplaisir J, Arrigoni J, Guilleminault C, Dement WC, et al.
DQB1-0602 (DQw1) is not present in most nonDR2 Caucasian narcoleptics.
Sleep. 1992 Oct;15(5):415-22.
"Human narcolepsy is a genetically determined disorder of sleep strongly associated with the human leucocyte antigens (HLA) DR2 and DQw1. In black narcoleptic patients, susceptibility for narcolepsy is more closely related to a specific gene subtype of DQw1, DQB1-0602, than to DR2. About 30% of black narcoleptic patients are nonDR2, but all carry the HLA DQB1-0602 gene. In the present study, we have tested caucasian nonDR2 cataplectic patients (6 sporadic cases and 7 familial cases from 3 multiplex families) for the presence of the HLA DQB1-0602 and DQA1-0102 (DQw1) using a specific polymerase chain reaction (PCR)-oligotyping technique. None of the patients was DQB1-0602 or DQA1-0102 positive, thus proving that, in caucasians, DQB1-0602 and DQA1-0102 (DQw1) are not prerequisites for the diagnosis of narcolepsy. Further studies with more patients are warranted to exclude the possibility that a few caucasian patients carry rare haplotypes with DQB1-0602 independently of DR2." [Abstract]

Xiao Y, Huang X, Qiu C, et Al.
[Extensive HLA class II studies in Chinese narcoleptic patients]
Zhonghua Nei Ke Za Zhi. 1999 Nov;38(11):757-9.
"OBJECTIVE: Narcolepsy is a debilitating, lifelong sleep disorder. Its familial occurrence suggests that genetic factors may be of importance in the etiology. Narcolepsy is a very rare disease among Chinese, thus it was of interest to study the association of narcolepsy with the HLA system in Chinese narcoleptic patients. METHODS: To explore the role of HLA-DRB genes in the development of narcolepsy, we studied 10 narcoleptic patients and 50 race matched controls in whom HLA-DR typing was perfomed by the method of DNA amplification with sequence-specific primers (PCR-SSP). RESULTS: All narcoleptic patients were found to be of DRB1 * 1501 and DRB5 * 0101 genotype. CONCLUSION: These results indicate that HLA-DRB1 * 1501 is a better primary candidate susceptibility gene for narcolepsy in Chinese." [Abstract]

Han F, Chen EZ, Wei HL, Dong XS, Li J, Li M, He QY, Ding DJ.
[HLA-DRB and -DQB allele contribution to narcolepsy susceptibility in Chinese patients with narcolepsy]
Zhonghua Yi Xue Za Zhi. 2003 Apr 25;83(8):644-6.
"OBJECTIVES: To study the association of narcolepsy with HLA class II alleles in Chinese narcoleptic patients. METHODS: 31 patients with narcolepsy underwent brain computed tomography (CT) scan and magnetic resonance imaging (MRI) testing. All patients received a MSLT test following a routine night's sleep, and serological HLA typing for HLA DR(2). 21 patients received PCR-SSP HLA DR and DQ typing. RESULTS: All patients had sleepiness and cataplexy. There was no evidence for other functional or structural diseases. Sleep paralysis was elicited in 45%; hypnagogic hallucinations, in 61%. Mean sleep latency on MSLT was 2.1 min +/- 1.3 min; sleep-onset rapid eye movement (SOREM) occurred during 2/5 naps in 30 of 31 patients. The average number and latency of SOREM episodes were 4.2 +/- 1.0 episodes and 4.0 min +/- 1.8 min, respectively. All patients but one were HLA DR(2) positive and 86% were HLADRB(1) * 1501-HLADQB(1)*0602 positive. CONCLUSIONS: HLA DR(2) and HLADQw6 are markers for narcolepsy-cataplexy in Chinese." [Abstract]

Planelles D, Puig N, Beneto A, Gomez E, Rubio P, Mirabet V, Bonanad S, Blasco I, Montoro JA.
HLA-DQA, -DQB and -DRB allele contribution to narcolepsy susceptibility.
Eur J Immunogenet. 1997 Dec;24(6):409-21.
"The association of narcolepsy with HLA class I antigens and HLA class II alleles was studies in a series of Spanish narcoleptic patients. The haplotype DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0602 was found to be significantly associated with the disease, while the haplotype DRB1*0701-DRB4*01-DQA1*0201-DQB1*02 might confer a slight protective effect against narcolepsy. Gene dose-effect was not seen in any of the involved alleles, and linkage disequilibrium between the positively associated alleles was found to be stronger in patients than in controls. Statistical analysis applied to identify the HLA allele truly responsible for the association did not clearly discriminate between the contribution of DRB1*1501 and that of DQB1*0602, but it proved that the association with DQA1*0102 is secondary to that with DRB1*1501/DQB1*0602. Analysis of the diagnostic value of typing for the narcolepsy-associated alleles demonstrated a very high negative predictive value and revealed that this test can be convenient for exclusion of narcolepsy in cases when the diagnosis is not evident after clinical evaluation and the marker haplotype is absent. Finally, a family study indicated that narcolepsy is a multifactorial disorder that involves HLA genes under an incomplete penetrance model, with possible influences from environmental factors or other genes different to HLA genes." [Abstract]

Ellis MC, Hetisimer AH, Ruddy DA, Hansen SL, Kronmal GS, McClelland E, Quintana L, Drayna DT, Aldrich MS, Mignot E.
HLA class II haplotype and sequence analysis support a role for DQ in narcolepsy.
Immunogenetics. 1997;46(5):410-7.
"A systematic haplotype and sequencing analysis of the HLA-DR and -DQ region in patients with narcolepsy was performed. Five new (CA)n microsatellite markers were generated and positioned on the physical map across the HLA-DQB1-DQA1-DRB1 interval. Haplotypes for these new markers and the three HLA loci were established using somatic cell hybrids generated from patients. A four-marker haplotype surrounding the DQB1(*)0602 gene was found in all narcolepsy patients, and was identical to haplotypes observed on random chromosomes harboring the DQB1(*)0602 allele. Eighty-six kilobases of contiguous genomic sequence across the region did not reveal new genes, and analysis of this sequence for single nucleotide polymorphisms did not reveal sequence variation among DQB1(*)0602 chromosomes. These results are consistent with other studies, suggesting that the HLA-DQ genes themselves are among the predisposing factors in narcolepsy." [Abstract]

Mignot E, Young T, Lin L, Finn L.
Nocturnal sleep and daytime sleepiness in normal subjects with HLA-DQB1*0602.
Sleep. 1999 May 1;22(3):347-52.
"Narcolepsy, a neurological disorder characterized by excessive daytime sleepiness and abnormal REM sleep, is known to be tightly associated with the Human Leukocyte Antigen (HLA) DQ allele DQB1*0602. In this study, we have explored the possibility that normal subjects carrying this HLA allele (25% of the general population) could display subclinical REM sleep abnormalities and increased daytime sleepiness. Data from 525 middle-aged adults enrolled in the Wisconsin Sleep Cohort study were used for this analysis. Nocturnal polysomnography, sleep latency during the multiple sleep latency test (MSLT), and questionnaire items pertaining to excessive daytime sleepiness were compared between DQB1*0602 positive (n = 132) and negative (n = 393) participants. Results indicate shorter REM latency whether or not the latency was adjusted for wake after sleep onset (p = 0.003) and p = 0.02 respectively), increased sleep efficiency (p = 0.06) and decreased percent time spent in stage I sleep (p = 0.02) during nocturnal polysomnography in DQB1*0602 subjects. Data gathered using the Multiple Sleep Latency Test or the Epworth and Stanford sleepiness scales did not differentiate between DQB1*0602 positive and negative subjects. These results support the hypothesis that polymorphisms at the level of HLA DQ modulates sleep tendencies in humans." [Abstract]

Mayer G, Lattermann A, Mueller-Eckhardt G, Svanborg E, Meier-Ewert K.
Segregation of HLA genes in multicase narcolepsy families.
J Sleep Res. 1998 Jun;7(2):127-33.
"In the past 15 years, 411 sporadic narcolepsy patients have been diagnosed in the Hephata Klinik, Schwalmstadt, Germany. They were explored for presence or absence of excessive daytime sleepiness and narcolepsy in their relatives. A subset of 39 patients were explored for presence or absence of parasomnias. Six patients had more than one relative affected by narcolepsy-cataplexy. Forty-seven family members were investigated with the Stanford Center for Narcolepsy Sleep Inventory and a standardized parasomnia questionnaire. Twenty-four relatives had nocturnal polysomnographies and Multiple Sleep Latency Tests. HLA class I typing was performed in all sporadic and familial cases, class II and microsatellite typing was performed in all members of multicase families. Based on the Finnish prevalence study by Hublin et al., 1994, the relative risk for first degree relatives to develop narcolepsy-cataplexy was in our sample 16.5, 34.2 for excessive daytime sleepiness and 426.9 for parasomnias. Cataplexy, excessive daytime sleepiness and single narcoleptic symptoms in the multicase families segregate with the DRBI*1501, CARII:200, CARI: 103, DQBI*0602 haplotype. In two families, members with narcolepsy and isolated symptoms have inherited the DRBI*1501/DQBI*0602 haplotype from the nonaffected parent. The observed segregations in these two families may support the view that narcoleptic symptoms are expressed by DRBI*1501/DQBI*0602 carriers, independent of haplotype origin. Parasomnias do not segregate with a specific haplotype. The frequency of parasomnias in narcolepsy is much higher than in the general population. The empirical risk for first degree family members of narcolepsy patients to develop cataplexy seems to be low, whereas it is higher for EDS and highest for parasomnias." [Abstract]

Dormoy A, Froelich N, Parissiadis A, Cazenave JP, Tongio MM.
Second HLA-A*68 null allele, A*6818 N, identified.
Tissue Antigens. 2002 Jul;60(1):88-90.
"A second HLA-A*68 null allele, HLA-A*6818 N, was identified in our laboratory after discrepant results were obtained between class I serological and molecular typing in a male patient suffering from narcolepsy. HLA-A*6818 N displays a sequence identical to that of the HLA-A*6802 allele, except in exon 2 where 20 nucleotides inserted at codon position 48 are a repeat of the 20 preceding nucleotides. This duplication creates a shift of the reading frame, which leads to a premature non-sense codon at position 59 of the null allele." [Abstract]

Roushdy J, Santoso S, Kalb R, Meier-Ewert K, Albert ED, Mueller-Eckhardt G.
A deletion in the second exon of an HLA-DRB1 allele found in a DR2-negative narcolepsy patient.
Hum Immunol. 1993 May;37(1):1-6.
"In this report, we describe a new allele of the HLA-DRB 1 gene carrying a form of mutation that has not been observed before. It appeared in an HLA-DR2-negative narcolepsy patient who, besides HLA-DR4, revealed a serologic HLA-DR blank segregating with HLA-DQ1. Oligotyping showed that the new allele belongs to the HLA-DR8 group. Restriction analysis and DNA sequencing revealed the deletion of 12 bp as well as the substitution of 9 flanking base pairs between codons 36 and 43. The expression of the mutated gene was demonstrated by the presence of its messenger RNA and a few positive reactions with DR8 sera. Without interrupting the reading frame, the mutation leads to a gene product composed of a modified amino acid sequence. We anticipate that the mutation influences the conformation of the molecule with possible consequences concerning immune response." [Abstract]

Wu HS, Guo YH, Zou LP, Han F, Zhang WC, Fang F, Xiao J, Ding CH, Li J, Chen CH
[Diagnosis of childhood narcolepsy and significance of HLA in its diagnosis]
Zhonghua Er Ke Za Zhi. 2004 Apr;42(4):248-51.
OBJECTIVE: Narcolepsy is a lifelong sleep disorder characterized by excessive daytime sleepiness, and features of rapid eye movement (REM) sleep, such as cataplexy, sleep paralysis and hypnagogic hallucinations. The present study aimed to investigate the diagnostic basis of childhood narcolepsy and possible role of HLA Class II alleles in the onset of this disease. METHODS: The clinical data of 40 narcoleptic children were analyzed. All patients received Multiple Sleep Latency Test (MSLT) and they were analyzed in combination with clinical features. Polymerase chain reaction/sequence specific primers (PCR/SSP) methods were used to detect the HLA-DRB1 and DQB1 alleles. RESULTS: Narcolepsy was diagnosed in 40 children. The age range was 3 to 14 years (mean 8.5 +/- 2.5 years), 29 were male and 11 female. Their mean course of disease was 6.5 months, 14 patients (30%) were less than 3 months old, 21 patients (52%) were less than 6 months old. All the patients had excessive daytime sleepiness, cataplexy appeared in 37 cases, hypnagogic hallucination in 22 and sleep paralysis in 6. Mean sleep latency on MSLT was less than 5 min, the average number of sleep-onset rapid eye movement (SOREM) was 4.33 +/- 0.26 episodes (2-5 episodes), the latency of SOREM episodes were 4.0 +/- 1.8 min (0.25-4.9 min). Thirty-five patients were DRB1 1501 and DQB1 0602 positive (Pc < 0.01), 2 were DRB1 1502 and DQB1 0601 positive, while 3 were DRB1 15 and DQB1 6 negative. CONCLUSIONS: Some pediatric patients with narcolepsy were different from adult patients in that the pediatric cases had a sudden onset and shorter disease course. Diagnosis of this disease was based on the clinical manifestations, MSLT and absence of any medical or psychiatric disorder that could account for the symptoms. The authors demonstrated that DRB1 1501 and DQB1 0602 were susceptibility genes for narcolepsy and those who were DRB1 15 negative could not be excluded. [Abstract]

Wieczorek S, Gencik M, Rujescu D, Tonn P, Giegling I, Epplen JT, Dahmen N.
TNFA promoter polymorphisms and narcolepsy.
Tissue Antigens. 2003 Jun;61(6):437-42.
"Narcolepsy is a debilitating sleep disorder that affects up to 0.05% of individuals in Caucasian populations. It is highly associated with the HLA-DR2 group antigen or the HLA-DRB1*1501-DQB1*0602 haplotype, respectively. However, the HLA association by itself cannot sufficiently explain the increased risk to family members, as HLA-DR2 is quite common in the general population and most people harboring the respective genotype do not develop any symptoms of narcolepsy. Situated in the HLA class II region, the TNFA gene is translated into the pro-inflammatory cytokine TNF-alpha. TNFA promoter polymorphisms have been linked to several inflammatory and autoimmune diseases. We analyzed three SNP of the TNFA promoter and one adjacent microsatellite in 103 patients and 96 controls. The T-allele of the C-857T polymorphism was strongly associated with narcolepsy in the subgroup of DRB1*15/16 (HLA-DR2 type) negative patients, but not in DRB1*15/16 positive patients. These results point towards an etiological influence of TNFA alleles in narcolepsy and support previous findings suggesting genetic heterogeneity and differences in pathophysiological characteristics of HLA-DR2 positive and negative narcolepsy." [Abstract]

Hohjoh H, Nakayama T, Ohashi J, Miyagawa T, Tanaka H, Akaza T, Honda Y, Juji T, Tokunaga K.
Significant association of a single nucleotide polymorphism in the tumor necrosis factor-alpha (TNF-alpha) gene promoter with human narcolepsy.
Tissue Antigens. 1999 Aug;54(2):138-45.
"Narcolepsy is a sleep disorder in which multiple factors, including environmental and genetic factors, are involved. A genetic factor strongly associated with the disorder has been found in the human leukocyte antigen (HLA) class II region: the haplotype, DRB1*1501-DQB1*0602, predisposes to narcolepsy. No susceptibility genes other than the HLA-haplotype have been found. In this paper, we performed an association study of the tumor necrosis factor-alpha (TNF-alpha) gene located in the HLA class III region with human narcolepsy, in which we examined the known single-nucleotide polymorphisms (SNPs) in the promoter region in 49 narcoleptic patients, who were all positive for DRBI*1501, and 111 healthy control individuals. The results indicated that the frequency of the genotype at position -857 (-857SNP) was significantly different between the patients and controls, and the allele frequencies of 857SNP revealed that the frequency of -857T was significantly increased in the patients as compared with that in the controls (P=0.0068). In addition, haplotypes presumed from HLA-DRB1, -857SNP and HLA-B loci suggested that -857T was mainly associated with DRB1 alleles other than DRB1*1501: the significant increase in frequency of -857T in the patients was not caused by allelic association with DRB1*1501. Therefore, it is conceivable that the TNF-alpha with 857T was associated with narcolepsy independently of the strong association of DRB1*1501 with the disorder. Altogether, the data presented here lead us to propose that TNF-alpha could be a new susceptibility gene in human narcolepsy." [Abstract]

Hohjoh H, Terada N, Nakayama T, Kawashima M, Miyagawa T, Honda Y, Tokunaga K.
Case-control study with narcoleptic patients and healthy controls who, like the patients, possess both HLA-DRB1*1501 and -DQB1*0602.
Tissue Antigens. 2001 Mar;57(3):230-5.
"In previous studies, we suggested that the tumor necrosis factor (TNF-alpha and its receptor 2 (TNFR2) genes could be associated with the susceptibility to human narcolepsy, and that haplotype carrying DRB1*1502 had a negative association with the disorder. To further evaluate these associations, we herein compared narcoleptic patients with healthy individuals who, like the patients, possessed both DRB1*1501 and DQB1*0602. Results agreed with the negative association of DRB1*1502 and positive association of the TNF-alpha(-857T) and TNFR2-196R combination with the disorder. In addition, a significant association of the TNF-alpha(-857T) homozygote with the disorder and an increase in a rare haplotype carrying DRB1*1501 and TNF-alpha(-857T) in the patients were also observed in the present study." [Abstract]

Hohjoh H, Terada N, Miki T, Honda Y, Tokunaga K.
Haplotype analyses with the human leucocyte antigen and tumour necrosis factor-alpha genes in narcolepsy families.
Psychiatry Clin Neurosci. 2001 Feb;55(1):37-9.
"Our previous study suggested that the tumour necrosis factor-alpha gene with thymine residue at position -857 in its promoter region [TNF-alpha(-857T)] could be associated with human narcolepsy independently of a strong association of the human leucocyte antigen (HLA)-DRB1*1501 with the disorder. To understand the relationship of DRB1*1501 with TNF-alpha(-857T) in narcoleptic patients, we investigated 28 members of four Japanese narcolepsy families and determined the haplotypes with the HLA-B, TNF-alpha(-857C/T) and HLA-DRB1 in the members. The resultant haplotypes indicated that not only the DRB1*1501-TNF-alpha(-857C) haplotype but also the DRB1*1501-TNF-alpha(-857T) haplotype, which is rare in healthy individuals and may have a strong predisposition to the disorder, were present in the affected members. From the chromosomal recombination observed in a few members, it is possible that chromosomal recombination could play a role in the generation of the rare DRB1*1501-TNF-alpha(-857T) haplotype." [Abstract]

Kato T, Honda M, Kuwata S, Juji T, Fukuda M, Honda Y, Kato N.
A search for a mutation in the tumour necrosis factor-alpha gene in narcolepsy.
Psychiatry Clin Neurosci. 1999 Jun;53(3):421-3.
"The discovery of almost 100% association of narcolepsy with human leukocyte antigens (HLA) DR2 antigen prompted molecular biological research of this disorder. In the HLA class II gene cluster, the gene for tumour necrosis factor-alpha (TNF-alpha), which plays a role in the regulation of normal human sleep, is located. The present study searched for a mutation in the TNF-alpha gene by single-strand conformation polymorphism analysis (SSCP) in patients with narcolepsy. No mutation was detected in exons and introns of the TNF-alpha gene by SSCP and sequencing." [Abstract]

Kato T, Honda M, Kuwata S, Juji T, Kunugi H, Nanko S, Fukuda M, Honda Y.
Novel polymorphism in the promoter region of the tumor necrosis factor alpha gene: No association with narcolepsy.
Am J Med Genet. 1999 Aug 20;88(4):301-4.
"The striking evidence of almost 100% association of narcolepsy with human leukocyte antigens (HLA) DR2(DR15) antigen is an important clue to elucidate the molecular basis of this sleep disorder. The gene for tumor necrosis factor alpha (TNF alpha) is located in the HLA class II gene cluster. Recent studies have indicated that TNF alpha plays an important role in the regulation of normal human sleep, and regulation of this cytokine may be disturbed in narcolepsy. We searched for a mutation associated with narcolepsy in the promoter region of the TNF alpha gene by single-strand conformation polymorphism analysis. A novel polymorphism, C-850T, was found in narcoleptic patients. Genotype frequency was examined by restriction fragment length polymorphism method. No significant difference of genotype distribution was found between 92 patients with narcolepsy and 91 normal controls. These results do not support our hypothesis that genetic abnormality of TNF alpha production is pathogenetic for narcolepsy." [Abstract]

Wieczorek S, Dahmen N, Jagiello P, Epplen JT, Gencik M.
Polymorphisms of the tumor necrosis factor receptors: no association with narcolepsy in German patients.
J Mol Med. 2003 Feb;81(2):87-90. Epub 2003 Feb 11.
"Narcolepsy is a debilitating sleep disorder characterized by daytime sleepiness and cataplexy. The strong association of narcolepsy with the HLA system suggests an autoimmune cause. Tumor necrosis factor is a cytokine involved in both regulation of immune mechanisms and sleep. Several studies were undertaken to determine a contribution of tumor necrosis factor and its receptors to the pathogenesis of narcolepsy. A significant increase in the 196R allele, a functionally relevant polymorphism in the TNFR2 gene, has been found in Japanese patients, indicating altered transduction of tumor necrosis factor signals. Here we explore polymorphisms in both tumor necrosis factor receptor genes as risk factors in a German population sample. Neither the polymorphism in the TNFR1 nor that in the TNFR2 gene was associated with narcolepsy. Our findings contrast to those previously published and thus provide evidence for genetic heterogeneity between different narcolepsy populations." [Abstract]

Hohjoh H, Terada N, Kawashima M, Honda Y, Tokunaga K.
Significant association of the tumor necrosis factor receptor 2 (TNFR2) gene with human narcolepsy.
Tissue Antigens. 2000 Nov;56(5):446-8.
"We report on the association study of the tumor necrosis factor receptor 2 (TNFR2) gene with human narcolepsy. A single-nucleotide polymorphism in TNFR2, which is involved in an amino acid substitution [methionine(M)/arginine(R)] at position 196, was investigated in 149 Japanese narcoleptic patients and 204 healthy individuals as controls. Results reveal that the frequency of the TNFR2-196R allele significantly increased in the patients as compared with that in the controls (P=0.029), suggesting that TNFR2 is likely associated with the susceptibility to narcolepsy. In addition, the analyses of the relationship of TNFR2 and TNF-alpha with the susceptibility to narcolepsy indicate the possibility that an additive effect on the susceptibility to the disorder lies between TNFR2-196R and TNF-alpha(-857T) alleles." [Abstract]

Wieczorek S, Dahmen N, Kasten M, Epplen JT, Gencik M
A rare form of narcolepsy (HLA-DR2-) shows possible association with (functionally relevant) alpha-interferon gene polymorphisms.
Psychiatr Genet. 2004 Mar;14(1):47-51.
Narcolepsy is a neuropsychiatric disease caused by complex disturbance of sleep regulation. The main symptoms comprise daytime sleepiness and cataplexy. Although the aetiology remains unclear so far, narcolepsy is genetically characterized by strong linkage to the human leukocyte antigen complex as more than 90% of the patients are typed HLA-DR2+. Recently, it has become apparent that the orexin (hypocretin) neurotransmitter system plays a key role in the pathogenesis of the disease. Canine narcolepsy is caused by mutations in the orexin receptor 2 gene, and narcoleptic patients show specifically decreased cerebrospinal fluid orexin levels. Decreased promotor activity of the prepro-orexin gene is caused by binding of alpha-interferon in vitro. To investigate the possible role of IFNA gene polymorphisms in the pathogenesis of narcolepsy, we have genotyped two single nucleotide polymorphisms in IFNA genes as well as a neighbouring microsatellite. No association was evident in the prevalent DR2+ group. Yet, the IFNA10 single nucleotide polymorphisms and the IFNA microsatellite are associated with the DR2- patient group. Thus, the pathogenetic role of interferons needs to be defined in DR2- narcolepsy. [Abstract]

Nakayama J, Miura M, Honda M, Miki T, Honda Y, Arinami T.
Linkage of human narcolepsy with HLA association to chromosome 4p13-q21.
Genomics. 2000 Apr 1;65(1):84-6.
"Although narcolepsy is highly associated with human leukocyte antigen (HLA) DQ6/DQB1*0602 and/or DR2/DRB1*1501, most individuals with the HLA haplotype are free of narcolepsy. This indicates that HLA alone makes a relatively small contribution to the development of narcolepsy and that a non-HLA gene(s) can contribute to the genetic predisposition even in narcoleptic cases with HLA association. We conducted a genome-wide linkage search for narcolepsy in eight Japanese families with 21 DR2-positive patients (14 narcoleptic cases with cataplexy and 7 cases with an incomplete form of narcolepsy). A lod score of 3.09 suggested linkage to chromosome 4p13-q21. A lod score of 1.53 was obtained at the HLA-DRB1 locus, though this lod score may be biased since all the affected patients and many of the family members were DR2-positive. No other loci including hypocretin, hypocretin receptor 1, and hypocretin receptor 2 had lod scores greater than 1.0. The present study suggests that chromosome 4p13-q21 contains a second locus for HLA-associated human narcolepsy." [Abstract]

Tafti M, Dauvilliers Y.
Pharmacogenomics in the treatment of narcolepsy.
Pharmacogenomics. 2003 Jan;4(1):23-33.
"Narcolepsy is a neurological disorder characterized by excessive daytime sleepiness and cataplexy. Available treatments of narcolepsy include stimulants and antidepressants but the recent discovery of orexin/hypocretin deficiency in narcolepsy opens up new perspectives. Narcolepsy is a complex disorder involving genetic, immune and environmental factors. Although only a strong association is found with the HLA DQB1*0602 gene, other genetic susceptibility factors might be involved. Among these, the functional polymorphism of the catechol-O-methyltransferase (COMT) gene is critically involved in the severity of narcolepsy and in the response to the stimulant modafinil. Other pharmacogenetic targets include the orexinergic, noradrenergic and possibly the serotonergic pathways." [Abstract]

Dauvilliers Y, Neidhart E, Lecendreux M, Billiard M, Tafti M.
MAO-A and COMT polymorphisms and gene effects in narcolepsy.
Mol Psychiatry. 2001 Jul;6(4):367-72.
"Narcolepsy presents one of the tightest associations with a specific HLA antigen (DQB1*0602) but there is strong evidence that non-HLA genes also confer susceptibility. Recent observations have implicated the hypocretin/orexin system in narcolepsy in both humans and animals. In addition, the implication of monoaminergic systems in the pathophysiology of narcolepsy is well established and a significant association between the monoamine oxydase-A (MAO-A) gene and human narcolepsy has recently provided a possible genetic link. We investigated polymorphisms of MAO-A and catechol-O-methyltransferase (COMT) in 97 Caucasians with well-defined narcolepsy-cataplexy and sought for genotypic effects on disease symptoms. No evidence of association between genotype or allele frequencies of both MAO-A or COMT gene and narcolepsy was found. However, a sexual dimorphism and a strong effect of COMT genotype on disease severity were found. Women narcoleptics with high COMT activity fell asleep twice as fast as those with low COMT activity during the multiple sleep latency test (MSLT) while the opposite was true for men. COMT genotype also strongly affected the presence of sleep paralysis and the number of REM sleep onsets during the MSLT. In agreement with well-documented pharmacological results in canine narcolepsy, this study reports the first genetic evidence for the critical involvement of the dopaminergic and/or noradrenergic systems in human narcolepsy." [Abstract]

Dauvilliers Y, Neidhart E, Billiard M, Tafti M.
Sexual dimorphism of the catechol-O-methyltransferase gene in narcolepsy is associated with response to modafinil.
Pharmacogenomics J. 2002;2(1):65-8.
"The gene for catechol-O-methyltransferase (COMT) plays a key modulatory role in dopaminergic and noradrenergic neurotransmission. Recent evidence suggests that modafinil, like other stimulants, might act through the dopaminergic system. We have reported a sexual dimorphism and a strong effect of the COMT genotype on narcolepsy symptoms and hypothesized that response to modafinil treatment may be associated with the COMT genotype. Here we confirm that COMT genotype distribution between men and women narcoleptics is associated with response to modafinil. In addition, the optimal daily dose of modafinil is approximately 100 mg lower in women narcoleptics and lower in all narcoleptics with low activity COMT genotype. Our results suggest that a sexual dimorphism in COMT activity affects the response to modafinil and probably to other dopaminergic stimulants." [Abstract]

Wieczorek S, Jagiello P, Arning L, Dahmen N, Epplen JT
Screening for candidate gene regions in narcolepsy using a microsatellite based approach and pooled DNA.
J Mol Med. 2004 Oct;82(10):696-705.
Narcolepsy is a complex sleep disorder characterized by excessive daytime sleepiness and cataplexy. Mutations in genes of the hypocretin (orexin) neurotransmitter system cause narcoleptic symptoms in animal models. The absence of hypocretin in the cerebrospinal fluid of human patients is hypothesized to originate from destruction of hypocretinergic cells in the hypothalamus, the cause of which remains unknown. Due to strong HLA association autoimmune models of narcolepsy pathogenesis are still mostly favored. Genetic predisposition factors other than HLA are likely to play a role in causing the disorder. We screened three sets of gene regions ( n=254) for association with narcolepsy using a microsatellite based approach and pooled DNA: genes related to immunity, particularly apoptosis; genes related to regulation of circadian rhythmicity; genes coding for several factors of neurotransmission. In relation to apoptosis an association was found for the BAG1 gene region. Interestingly, microsatellites representing four genomic regions related to neurotransmission revealed association with narcolepsy: COMT, DRD2, GABBR1, and HTR2A. These results, although exploratory and still to be confirmed in independent samples, support a complex pathogenetic model for narcolepsy, including disturbances of neurotransmission rather than involvement of autoimmunity. [Abstract]

Dauvilliers Y, Blouin JL, Neidhart E, Carlander B, Eliaou JF, Antonarakis SE, Billiard M, Tafti M
A narcolepsy susceptibility locus maps to a 5 Mb region of chromosome 21q.
Ann Neurol. 2004 Sep;56(3):382-8.
The genetic basis of human narcolepsy remains poorly understood. Multiplex families with full-blown narcolepsy-cataplexy are rare, whereas families with both narcolepsy-cataplexy and excessive daytime sleepiness without cataplexy are more common. We performed a genomewide linkage analysis in a large French family with four members affected with narcolepsy-cataplexy and 10 others with isolated recurrent naps or lapses into sleep. Only three regions showed logarithm of odds (LOD) scores greater than 1 in two-point linkage analysis (D6S1960, D11S2359, and D21S228). Genotyping additional markers provided support for linkage to 9 markers on chromosome 21 (maximum two-point LOD score, 3.36 at D21S1245). The multipoint linkage analysis using SimWalk2 provided further evidence for linkage to the same region (maximum parametric LOD score, 4.00 at 21GT26K). A single haplotype was shared by all affected individuals and informative crossovers indicated that the elusive gene that confers susceptibility to narcolepsy is likely to be located between markers D21S267 and ABCG1, in a 5.15 Mb region of 21q. [Abstract]

Douglass AB.
Narcolepsy: differential diagnosis or etiology in some cases of bipolar disorder and schizophrenia?
CNS Spectr. 2003 Feb;8(2):120-6.
"Does narcolepsy, a neurological disease, need to be considered when diagnosing major mental illness? Clinicians have reported cases of narcolepsy with prominent hypnagogic hallucinations that were mistakenly diagnosed as schizophrenia. In some bipolar disorder patients with narcolepsy, the HH resulted in their receiving a more severe diagnosis (ie, bipolar disorder with psychotic features or schizoaffective disorder). The role of narcolepsy in psychiatric patients has remained obscure and problematic, and it may be more prevalent than commonly believed. Classical narcolepsy patients display the clinical "tetrad"--cataplexy, hypnagogic hallucinations, daytime sleep attacks, and sleep paralysis. Over 85% also display the human leukocyte antigen marker DQB1*0602 (subset of DQ6). Since 1998, discoveries in neuroanatomy and neurophysiology have greatly advanced the understanding of narcolepsy, which involves a nearly total loss of the recently discovered orexin/hypocretin (hypocretin) neurons of the hypothalamus, likely by an autoimmune mechanism. Hypocretin neurons normally supply excitatory signals to brainstem nuclei producing norepinephrine, serotonin, histamine, and dopamine, with resultant suppression of sleep. They also project to basal forebrain areas and cortex. A literature review regarding the differential diagnosis of narcolepsy, affective disorder, and schizophrenia is presented. Furthermore, it is now possible to rule out classical narcolepsy in difficult psychiatric cases. Surprisingly, psychotic patients with narcolepsy will likely require stimulants to fully recover. Many conventional antipsychotic drugs would worsen their symptoms and make them appear to become a "chronic psychotic," while in fact they can now be properly diagnosed and treated." [Abstract]

Miyagawa T, Hohjoh H, Honda Y, Juji T, Tokunaga K.
Identification of a telomeric boundary of the HLA region with potential for predisposition to human narcolepsy.
Immunogenetics. 2000 Nov;52(1-2):12-8.
"We report on a study performed to determine a boundary of the region with the potential to contribute to the predisposition to human narcolepsy (the susceptibility region) in the human leukocyte antigen (HLA) region. We investigated a Japanese narcolepsy family, in which a de novo chromosomal recombination occurred between the HLA-DRB1 and HLA-B genes in the proband. The recombinant chromosome carrying HLA-DRB1*1501 was transmitted to the affected child and grandchild, suggesting that a strong genetic factor(s) predisposing to the disorder was (were) present on the chromosome, and that the recombination breakpoint could be regarded as a boundary to the susceptibility region. To search for the breakpoint, we carried out allele typing at various polymorphic sites, e.g., microsatellite repeat polymorphisms, restriction fragment length polymorphisms, and single-nucleotide polymorphisms in the HLA region, and examined haplotypes with the polymorphic sites in the family members. Haplotype analyses revealed that the recombination breakpoint was present approximately 50 kb to the telomeric side of the palmitoyl-protein thioesterase-2 (PPT2) gene in the HLA class III region. From the gene map of the HLA region, the cyclic AMP response element-binding protein-related protein gene (CREB-RP) appeared to be located at the telomeric end in the 50-kb region. Therefore, the data presented here suggest that the susceptibility region for the disorder in the family is present on the centromeric side of the CREB-RP gene in the recombinant Chromosome 6 carrying HLA-DRB1*1501." [Abstract]

Ando A, Shigenari A, Naruse TK, Sugaya K, Juji T, Honda Y, Ikemura T, Inoko H.
Triplet repeat polymorphism within the NOTCH4 gene located near the junction of the HLA class II and class III regions in narcolepsy.
Tissue Antigens. 1997 Dec;50(6):646-9.
"A polymorphic (CTG)n microsatellite repeat was found in the signal peptide domain of the NOTCH4 gene located near the junction of the class II and class III regions of the human major histocompatibility complex. This gene belongs to a multigene family of NOTCH originally identified as a differential factor of neuronal cells. To ascertain whether the NOTCH4 gene is involved in the development of neurogenic disease, narcolepsy, which is known to be tightly associated with HLA-DR15, this microsatellite polymorphism of the (CTG)n repeat was analyzed in Japanese patients with narcolepsy One allele, 9 repetitions of CTG (Leu) was significantly increased in the patient group. However, the significant increase of this allele in the patient group could be explained by a strong linkage disequilibrium with the HLA class II alleles, DRB1*1501, DQA1*0102 and DQB1*0602, which were more strongly associated with the disease. These results suggest that the (CTG)n repeat polymorphism in NOTCH4 does not primarily determine the susceptibility to narcolepsy." [Abstract]

Singh SM, George CF, Ott RN, Rattazzi C, Guilleminault C, Dement WC, Mignot E.
IgH (mu-switch and gamma-1) region restriction fragment length polymorphism in human narcolepsy.
J Clin Immunol. 1996 Jul;16(4):208-15.
"To determine if the IgH locus is involved in genetic predisposition to human narcolepsy, restriction fragment length polymorphisms specific for the IgM and IgG cluster within this locus were studied in sporadic cases of the disease, as well as in five families with two or more affected individuals. Comparisons were made between control populations and both familial and sporadic cases and for patients with and without HLA-DR15 and DQB1*0602. RFLP analysis at the S mu and gamma-1 loci, which cover over 200 kb of 14q32.3, indicates that there is no evidence for any association between the IgH region and human narcolepsy." [Abstract]

Gencik M, Dahmen N, Wieczorek S, Kasten M, Gencikova A, Epplen JT.
ApoE polymorphisms in narcolepsy.
BMC Med Genet. 2001;2(1):9. Epub 2001 Aug 09.
"SUMMARY: BACKGROUND: Narcolepsy is a common neuropsychiatric disorder characterized by increased daytime sleepiness, cataplexy and hypnagogic hallucinations. Deficiency of the hypocretin neurotransmitter system was shown to be involved in the pathogenesis of narcolepsy in animals and men. There are several hints that neurodegeneration of hypocretin producing neurons in the hypothalamus is the pathological correlate of narcolepsy. The ApoE4 allele is a major contributing factor to early-onset neuronal degeneration in Alzheimer disease and other neurodegenerative diseases as well. METHODS: To clarify whether the ApoE4 phenotype predisposes to narcolepsy or associates with an earlier disease onset, we have genotyped the ApoE gene in 103 patients with narcolepsy and 101 healthy controls. RESULTS: The frequency of the E4 allele of the ApoE gene was 11% in the patient and 15% in the control groups. Furthermore, the mean age of onset did not differ between the ApoE4+ and ApoE4- patient groups. CONCLUSION: Our results exclude the ApoE4 allele as a major risk factor for narcolepsy." [Full Text]

Fehr C, Schleicher A, Szegedi A, Anghelescu I, Klawe C, Hiemke C, Dahmen N.
Serotonergic polymorphisms in patients suffering from alcoholism, anxiety disorders and narcolepsy.
Prog Neuropsychopharmacol Biol Psychiatry. 2001 Jul;25(5):965-82.
"1. Alterations in the serotonergic neurotransmission have been frequently described for patients suffering from alcoholism, anxiety disorders and narcolepsy. 2. The authors tested for association of the 5-HT2A receptor polymorphism (T102C) and the intron 7 tryptophan hydroxylase (TPH) polymorphism (A218C) among 176 alcohol dependent patients, 35 patients with panic disorder, 50 patients with generalized anxiety disorder, 55 patients with narcolepsy and 87 healthy controls. 3. Allele and genotype frequencies of the 5-HT2A receptor polymorphism (T102C), the intron 7 TPH polymorphism (A218C) were almost similar between the patients suffering from alcohol dependence, panic disorder, generalized anxiety disorder and narcolepsy. 4. There was no association between the 5-HT2A receptor polymorphism (T102C), the intron 7 TPH (A218C) polymorphisms and alcohol dependence, panic disorder, generalized anxiety disorder and narcolepsy in our subsets of German patients." [Abstract]

Fehr C, Szegedi A, Anghelescu I, Klawe C, Hiemke C, Dahmen N.
Sex differences in allelic frequencies of the 5-HT2C Cys23Ser polymorphism in psychiatric patients and healthy volunteers: findings from an association study.
Psychiatr Genet. 2000 Jun;10(2):59-65.
"Polymorphisms in the serotonergic system are believed to play a role in the etiology and treatment of different psychiatric illnesses. The 5-HT2C receptor gene is X-linked, with a frequent mutation at nucleotide 68 leading to a Ser-->Cys transition at amino acid 23. Recent studies have demonstrated an impaired function of 5-HT2C receptors and an increased production of the major noradrenergic metabolite 3-methoxy-4-hydroxyphenylethyleneglycol in the cerebrospinal fluid among the subjects carrying the Ser23 allele (Lappalainen et al., 1999). Biol. Psychiatry 46:821). We genotyped patients with alcohol dependence, panic disorder without agoraphobia, generalized anxiety disorder, narcolepsy and normal healthy volunteers for the 5-HT2C Cys23Ser polymorphism. 5-HT2C Cys23Ser allele frequencies and genotypes did not differ among patients with alcohol dependence, panic disorder, generalized anxiety disorder, narcolepsy and normal healthy volunteers. In an overall analysis, female subjects (n = 173) displayed a higher frequency of 5-HT2C Ser23 alleles as compared to males (n = 298, P = 0.0178). The potential mechanisms of the observed gender difference in allele frequencies, including transmission ratio distortion, are discussed." [Abstract]

Gencik, M., Dahmen, N., Wieczorek, S., Kasten, M., Bierbrauer, J., Anghelescu, I., Szegedi, A., Menezes Saecker, A. M., Epplen, J. T.
A prepro-orexin gene polymorphism is associated with narcolepsy
Neurology 2001 56: 115-117
"The orexin (hypocretin) neurotransmitter system was recently shown to be directly involved in the pathogenesis of narcolepsy in two animal models. Furthermore, decreased levels of orexin A in the CSF were shown in narcoleptic patients. To define any genetic contribution of orexin to the etiology of narcolepsy, the authors screened the entire prepro-orexin gene for mutations or polymorphisms in 133 patients suffering from narcolepsy. They report an association of a rare polymorphism in the prepro-orexin gene with narcolepsy in a cohort of 178 patients."

"The mutation analysis in the prepro-orexin revealed a sequence variation C3250T (reference accession number AF118885) in the 5' UTR, 22 bp 5' from the start codon. The 3250T allele was present in six of 178 narcoleptic patients, as well as in one healthy control subject out of 189 (p < 0.05, OR = 6.5)."
[Full Text]

Hungs, Marcel, Lin, Ling, Okun, Michele, Mignot, Emmanuel
Polymorphisms in the vicinity of the hypocretin/orexin are not associated with human narcolepsy
Neurology 2001 57: 1893-1895
"Human narcolepsy/cataplexy is associated with reduced hypocretin (orexin) transmission. A common preprophypocretin (HCRT) polymorphism (-909C/T) was identified and tested in 502 subjects (105 trio families, 80 Caucasian narcolepsy cases, and 107 Caucasian control subjects). This polymorphism was not associated with the disease. The promoter and 5' untranslated (5'URT) regions of the HCRT gene (-320 to +21 from ATG) were also sequenced in 281 subjects. None of the subjects carried -22T, a rare 5'UTR polymorphism previously reported to be associated with narcolepsy. The HCRT locus is not a major narcolepsy susceptibility locus." [Abstract]

Black JL, Silber MH, Krahn LE, Avula RK, Walker DL, Pankratz VS, Fredrickson PA, Slocumb NL
Studies of humoral immunity to preprohypocretin in human leukocyte antigen DQB1*0602-positive narcoleptic subjects with cataplexy.
Biol Psychiatry. 2005 Sep 15;58(6):504-9.
BACKGROUND: Canine models for narcolepsy have mutations of the hypocretin receptor 2 gene, and preprohypocretin knockout murine lines exhibit narcoleptic-like behaviors. Human narcolepsy with cataplexy is associated with human leukocyte antigen DQB1*0602 and reduced hypocretin levels in cerebrospinal fluid, suggesting an autoimmune diathesis. We tested the hypothesis that DQB1*0602-positive narcoleptic subjects with cataplexy have immunoglobulin (Ig)G reactive to human preprohypocretin and its cleavage products. METHODS: Serum samples of 41 DQB1*0602-positive narcoleptic subjects with cataplexy and 55 control subjects were studied, as were 19 narcoleptic and 13 control samples of cerebrospinal fluid. We tested for IgG reactive to preprohypocretin and its major cleavage products (including hypocretin 1 and 2), using immunoprecipitation assays (IP), immunofluorescence microscopy (IF) of Chinese hamster ovarian cells expressing preprohypocretin, and Western blots. RESULTS: There was no evidence for IgG reactive to preprohypocretin or its cleavage products in CSF of subjects with narcolepsy as measured by IPs, Western blots, and IF. Although the IP with CSF and the C-terminal peptide showed significant differences by two methods of comparison, the control subjects had higher counts per minute than narcoleptic subjects, which was opposite to our hypothesis. CONCLUSIONS: The hypothesis that DQB1*0602-positive narcoleptic subjects with cataplexy have IgG reactive to preprohypocretin or its cleavage products was not supported. [Abstract]

Khatami R, Maret S, Werth E, Rétey J, Schmid D, Maly F, Tafti M, Bassetti CL

Monozygotic twins concordant for narcolepsy-cataplexy without any detectable abnormality in the hypocretin (orexin) pathway.
Lancet. 2004 Apr 10;363(9416):1199-200.
Narcolepsy with cataplexy is thought to be a hypocretin ligand or hypocretin receptor deficiency syndrome caused by genetic and environmental factors. We looked for an abnormality of the hypocretin pathway in HLA-DQB1*0602-positive monozygotic twins who were concordant for narcolepsy-cataplexy. They had normal cerebrospinal fluid concentrations of hypocretin-1, and we found no mutation in the prepro-hypocretin gene or either hypocretin receptor gene. Our finding points to the existence of presumably genetic forms of narcolepsy with cataplexy without any demonstrable defect in the hypocretin pathway. [Abstract]

Moreira F, Pedrazzoli M, Dos Santos Coelho FM, Pradella-Hallinan M, Lopes da Conceição MC, Pereira Peregrino AJ, de Oliveira EC, Tufik S
Clock gene polymorphisms and narcolepsy in positive and negative HLA-DQB1*0602 patients.
Brain Res Mol Brain Res. 2005 Oct 31;140(1-2):150-4.
Narcolepsy is a chronic sleep disorder. It is linked to the HLA-DQB1*0602 allele. A recent report established a genetic linkage between narcolepsy and the chromosomal region 4p13-q21 that contains the Clock gene. We studied two SNPs in the Clock gene aiming to find any association with narcolepsy. We did not find differences in genetic frequencies in the patients group. We concluded that these two SNPs are not associated with narcolepsy. [Abstract]


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Recent Narcolepsy Genetic Research

1) Gotter AL, Roecker AJ, Hargreaves R, Coleman PJ, Winrow CJ, Renger JJ
Orexin receptors as therapeutic drug targets.
Prog Brain Res. 2012;198:163-88.
Orexin (hypocretin) receptor antagonists stand as a model for the development of targeted CNS small-molecule therapeutics. The identification of mutations in the gene for the orexin 2 receptor responsible for canine narcolepsy, the demonstration of a hypersomnolence phenotype in hypocretin knockout mice and the disruption in orexin signaling in narcoleptic patients provides clear genetic proof of concept for targeting orexin-induced arousal for the treatment of insomnia. The full characterization of the genes encoding orexin and its two cognate receptors enabled the rapid development of in vitro and ex vivo assays with which to identify lead compound structures and to optimize potency and pharmacokinetic properties. Polysomnographic measures with cross-species translatability capable of measuring the sleep-promoting effects of orexin receptor antagonists from mice to man, and the existence of knockout models not only allow efficacy assessment but also the demonstration of mechanism of action. Focused efforts by a number of groups have identified potent compounds of diverse chemical structure with differential orexin receptor selectivity for either the orexin 1 receptor (OX(1)R) or the orexin 2 receptor (OX(2)R), or both. This work has yielded tool compounds that, along with genetic models, have been used to specifically define the role these receptors in mediating orexin-induced arousal and vigilance state control. Optimized dual receptor antagonists with favorable pharmacokinetic and safety profiles have now demonstrated efficacy in clinical development and represent a distinct mechanism of action for the treatment of insomnia relative to current standard of care. [PubMed Citation] [Order full text from Infotrieve]

2) Bernardini C, Lattanzi W, Bosco P, Franceschini C, Plazzi G, Michetti F, Ferri R
Genome-wide gene expression profiling of human narcolepsy.
Gene Expr. 2012;15(4):171-81.
The objective of this study was to perform global gene expression profiling of patients affected by narcolepsy with cataplexy (NRLCP). This enabled identifying new potential biomarkers and relevant molecules possibly involved in the disease pathogenesis. In this study 10 NRLCP patients and 10 healthy controls were compared. Total RNA isolated from blood specimens was analyzed using microarray technology followed by statistical data analysis to detect genome-wide differential gene expression between patients and controls. Functional analysis of the gene list was performed in order to interpret the biological significance of the data. One hundred and seventy-three genes showed significant (p < 0.01) differential expression between the two tested conditions. The biological interpretation allowed categorizing differentially expressed genes involved in neurite outgrowth/extension and brain development, which could be possibly regarded as peripheral markers of the disease. Moreover, the NRLCP-related gene expression profiles indicated a dysregulation of metabolic and immune-related mechanisms. In conclusion, the gene expression profile associated to NRLCP suggested that molecular markers of neurological impairment, dysmetabolic and immune-related mechanisms, can be detected in blood of NRLCP patients. [PubMed Citation] [Order full text from Infotrieve]

3) Gotter AL, Webber AL, Coleman PJ, Renger JJ, Winrow CJ
International Union of Basic and Clinical Pharmacology. LXXXVI. Orexin Receptor Function, Nomenclature and Pharmacology.
Pharmacol Rev. 2012 Jul;64(3):389-420.
Orexin signaling is essential for normal regulation of arousal and behavioral state control and represents an attractive target for therapeutics combating insomnia. Alternatively termed hypocretins, these neuropeptides were named to reflect sequence similarity to incretins and their potential to promote feeding. Current nomenclature reflects these molecular and biochemical discovery approaches in which HCRT, HCRTR1, and HCRTR2 genes encode prepro-orexin, the orexin 1 receptor (OX(1)) and the orexin 2 receptor (OX(2))-gene names designated by the Human Genome Organization and receptor names designated by the International Union of Basic and Clinical Pharmacology. Orexinergic neurons are most active during wakefulness and fall silent during inactive periods, a prolonged disruption in signaling most profoundly resulting in hypersomnia and narcolepsy. Hcrtr2 mutations underlie the etiology of canine narcolepsy, deficiencies in orexin-producing neurons are observed in the human disorder, and ablation of mouse orexin neurons or the Hcrt gene results in a narcolepsy-cataplexy phenotype. The development of orexin receptor antagonists and genetic models targeting components of the orexin pathway have elucidated the OX(2) receptor-specific role in histamine-mediated arousal and the contribution of both receptors in brainstem pathways involved in vigilance state gating. Orexin receptor antagonists of varying specificity uncovered additional roles beyond sleep and feeding that include addiction, depression, anxiety, and potential influences on peripheral physiology. Combined genetic and pharmacological approaches indicate that orexin signaling may represent a confluence of sleep, feeding, and reward pathways. Selective orexin receptor antagonism takes advantage of these properties toward the development of novel insomnia therapeutics. [PubMed Citation] [Order full text from Infotrieve]

4) Klein G, Burghaus L, Diederich N
[Pathogenesis of Narcolepsy: From HLA Association to Hypocretin Deficiency.]
Fortschr Neurol Psychiatr. 2012 Jun 13;
Narcolepsy is a rare and chronic sleep disorder, characterised by excessive daytime sleepiness. Frequently associated signs are cataplexy, sleep paralysis and hypnagogic or hypnopompic hallucinations. Advances in understanding the pathogenesis of the disease have essentially been elucidated during the last fifteen years. The most significant finding has been the discovery of hypocretin-1 and -2 in 1998. Hypocretin-containing cells have widespread projections throughout the entire CNS and play a crucial role in the regulation of the sleep-wake cycle. They also contribute to olefaction and to the regulation of food intake. Animal models and human studies concordantly show that the disturbed hypocretin system is the probable cause of narcolepsy. However, it remains unclear why there is neuronal death of hypocretin-producing cells in the lateral hypothalamus. As the HLA-allele DQB1*0602 is associated with narcolepsy and hypocretin deficiency, an autoimmune reaction against hypocretin-producing neurons has been vigorously discussed. Newly discovered gene polymorphisms as well as previously unknown pathogenetic mechanisms, linking the sleep-wake cycle with the immune system, may also contribute to the pathogenetic cascade. Worthy of mention in this context is, e. g., the "insulin-like growth factor"-binding protein 3 (IGFBP3), whose overexpression causes a down-regulation of the hypocretin production. Substitution of the deficient neuropeptides by hypocretin agonists may become the causal treatment strategy of the future, if an adequate administration route can be found. Presently, animal trials, including genetic therapy, cell transplantations or the administration of hypocretin receptor agonists, are underway. [PubMed Citation] [Order full text from Infotrieve]

5) Tsunematsu T, Yamanaka A
The role of orexin/hypocretin in the central nervous system and peripheral tissues.
Vitam Horm. 2012;89:19-33.
Orexin, also called hypocretin, is a neuropeptide produced in neurons sparsely distributed in the lateral hypothalamic area. Orexin exhibits its physiological effects after binding two G-protein-coupled receptors, orexin 1 receptor and orexin 2 receptor. Impairment of the orexin signal, either by deletion of the prepro-orexin or orexin 2 receptor gene or by the ablation of orexin neurons, results in a sleep disorder similar to narcolepsy, suggesting that the orexin system plays an important role in the regulation of sleep/wakefulness. In addition, previous studies have suggested that orexin is involved in energy and fluid homeostasis, emotion regulation, stress responsiveness, and reward. However, growing evidence also suggests that orexin affects the function of peripheral tissues via direct activation of orexin receptors or through activation of autonomic nervous or endocrine systems. In this review, we discuss the physiological roles of orexin not only in the central nervous system but also in the peripheral tissues. [PubMed Citation] [Order full text from Infotrieve]

6) Barclay NL, Gregory AM
Quantitative genetic research on sleep: A review of normal sleep, sleep disturbances and associated emotional, behavioural, and health-related difficulties.
Sleep Med Rev. 2012 May 2;
Over the past 50 years, well over 100 twin studies have focussed on understanding factors contributing to variability in normal sleep-wake characteristics and sleep disturbances. Whilst we have gained a great deal from these studies, there is still much to be learnt. Twin studies can be used in multiple ways to answer questions beyond simply estimating heritability. This paper provides a comprehensive review of some of the most important findings from twin studies relating to sleep to date, with a focus on studies investigating genetic and environmental influences contributing to i) objective and subjective measures of normal sleep characteristics (e.g., sleep stage organisation, sleep quality); as well as sleep disturbances and disorders such as dyssomnias (e.g., insomnia, narcolepsy) and parasomnias (e.g., sleepwalking, bruxism); ii) the persistence of sleep problems from childhood to adulthood, and the possibility that the aetiological influences on sleep change with age; iii) the associations between sleep disturbances, emotional, behavioural and health-related problems; and iv) processes of gene-environment correlation and interaction. We highlight avenues for further research, emphasising the need to further consider the aetiology of longitudinal associations between sleep disturbances and psychopathology; the genetic and environmental overlap between sleep and numerous phenotypes; and processes of gene-environment interplay and epigenetics. [PubMed Citation] [Order full text from Infotrieve]

7) Han F
Sleepiness that cannot be overcome-narcolepsy and cataplexy.
Respirology. 2012 Apr 4;
Narcolepsy cataplexy syndrome is characterized by excessive daytime sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. It is strongly associated with the genetic marker, human leucocyte antigen (HLA) DQB1*06:02. A deficit in the endogenous hypocretin/orexin system due to neuronal degeneration in the lateral hypothalamus, induced by an autoimmune-mediated process, is the primary pathophysiology associated with the human disease. The important finding of an association with hypocretin genes in animal models of narcolepsy has led to the establishment of cerebrospinal fluid hypocretin measurements as a new diagnostic test for human narcolepsy. This is a fascinating story of translation of basic science research into clinical practice in sleep medicine during the past decade. Recent advances have shed light on the associations between respiratory medicine and narcolepsy cataplexy research. The first is that upper airway infections, including H1N1 and/or streptococcal infections, may initiate or reactivate an immune response that leads to loss of hypocretin secreting cells and narcolepsy in genetically susceptible individuals. The second is that an increased incidence of sleep disordered breathing among narcoleptic subjects may relate to the impairment of central control of breathing, linked to hypocretin deficiency or carriage of HLADQB1*06:02, in animals and human subjects with narcolepsy, respectively, indicating neural dysfunction in an area where respiratory and sleep-wake systems are closely interrelated. © 2012 The Author. Respirology © 2012 Asian Pacific Society of Respirology. [PubMed Citation] [Order full text from Infotrieve]

8) Partinen M, Saarenpää-Heikkilä O, Ilveskoski I, Hublin C, Linna M, Olsén P, Nokelainen P, Alén R, Wallden T, Espo M, Rusanen H, Olme J, Sätilä H, Arikka H, Kaipainen P, Julkunen I, Kirjavainen T
Increased incidence and clinical picture of childhood narcolepsy following the 2009 H1N1 pandemic vaccination campaign in Finland.
PLoS One. 2012;7(3):e33723.
[PubMed Citation] [Order full text from Infotrieve]

9) Sadasivan S, Pond BB, Pani AK, Qu C, Jiao Y, Smeyne RJ
Methylphenidate exposure induces dopamine neuron loss and activation of microglia in the basal ganglia of mice.
PLoS One. 2012;7(3):e33693.
[PubMed Citation] [Order full text from Infotrieve]

10) De la Herrán-Arita AK, Drucker-Colín R
Models for narcolepsy with cataplexy drug discovery.
Expert Opin Drug Discov. 2012 Feb;7(2):155-64.
INTRODUCTION: Narcolepsy is a chronic sleep disorder, characterized by a disrupted nocturnal sleep, excessive daytime sleepiness (EDS) and symptoms of dissociated rapid eye movement (REM) sleep. These symptoms are often disabling, confining the patients to a life-long pharmacologic symptomatic treatment. Nowadays, it is well known that narcolepsy results from alterations in the genes involved in the physiology of the orexin ligand or its receptor. AREAS COVERED: This review recapitulates on the current approaches for treating narcolepsy with cataplexy and the use of narcolepsy models in order to address different aspects of the disease. EXPERT OPINION: Animal models are required for the study of human diseases when it is impractical or unethical to use humans; these models are useful for studying the underlying causes of a disease and are a common research tool for identifying potential drug targets. Current treatment for human narcolepsy is symptomatically based; interestingly, the existing approaches do not target the orexinergic circuit. The discovery of novel drug targets for treating narcolepsy remains the primary focus of study in sleep medicine research. New therapies will arise through the discovery of new animal models of narcolepsy, which will offer new insights into the understanding of its physiopathology. [PubMed Citation] [Order full text from Infotrieve]

11) Winkelmann J, Lin L, Schormair B, Kornum BR, Faraco J, Plazzi G, Melberg A, Cornelio F, Urban AE, Pizza F, Poli F, Grubert F, Wieland T, Graf E, Hallmayer J, Strom TM, Mignot E
Mutations in DNMT1 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy.
Hum Mol Genet. 2012 May 15;21(10):2205-10.
Autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN) is characterized by late onset (30-40 years old) cerebellar ataxia, sensory neuronal deafness, narcolepsy-cataplexy and dementia. We performed exome sequencing in five individuals from three ADCA-DN kindreds and identified DNMT1 as the only gene with mutations found in all five affected individuals. Sanger sequencing confirmed the de novo mutation p.Ala570Val in one family, and showed co-segregation of p.Val606Phe and p.Ala570Val, with the ADCA-DN phenotype, in two other kindreds. An additional ADCA-DN kindred with a p.GLY605Ala mutation was subsequently identified. Narcolepsy and deafness were the first symptoms to appear in all pedigrees, followed by ataxia. DNMT1 is a widely expressed DNA methyltransferase maintaining methylation patterns in development, and mediating transcriptional repression by direct binding to HDAC2. It is also highly expressed in immune cells and required for the differentiation of CD4+ into T regulatory cells. Mutations in exon 20 of this gene were recently reported to cause hereditary sensory neuropathy with dementia and hearing loss (HSAN1). Our mutations are all located in exon 21 and in very close spatial proximity, suggesting distinct phenotypes depending on mutation location within this gene. [PubMed Citation] [Order full text from Infotrieve]

12) Weiner Lachmi K, Lin L, Kornum BR, Rico T, Lo B, Aran A, Mignot E
DQB1*06:02 allele-specific expression varies by allelic dosage, not narcolepsy status.
Hum Immunol. 2012 Apr;73(4):405-10.
The association of narcolepsy-cataplexy, a sleep disorder caused by the loss of hypocretin/orexin neurons in the hypothalamus, with DQA1*01:02-DQB1*06:02 is one of the tightest known single-allele human leukocyte antigen (HLA) associations. In this study, we explored genome-wide expression in peripheral white blood cells of 50 narcolepsy versus 47 controls (half of whom were DQB1*06:02 positive) and observed the largest differences between the groups in the signal from HLA probes. Further studies of HLA-DQ expression (mRNA and protein in a subset) in 125 controls and 147 narcolepsy cases did not reveal any difference, a result we explain by the lack of proper control of allelic diversity in Affymetrix HLA probes. Rather, a clear effect of DQB1*06:02 allelic dosage on DQB1*06:02 mRNA levels (1.65-fold) and protein (1.59-fold) could be demonstrated independent of disease status. These results indicate that allelic dosage is transmitted into changes in heterodimer availability, a phenomenon that may explain the increased risk for narcolepsy in DQB1*06:02 homozygotes versus heterozygotes. [PubMed Citation] [Order full text from Infotrieve]

13) Xiong H, Higaki K, Wei CJ, Bao XH, Zhang YH, Fu N, Qin J, Adachi K, Kumura Y, Ninomiya H, Nanba E, Wu XR
Genotype/phenotype of 6 Chinese cases with Niemann-Pick disease type C.
Gene. 2012 May 1;498(2):332-5.
[PubMed Citation] [Order full text from Infotrieve]

14) Woo HI, Joo EY, Hong SB, Lee KW, Kang ES
Use of PCR with sequence-specific primers for high-resolution human leukocyte antigen typing of patients with narcolepsy.
Ann Lab Med. 2012 Jan;32(1):57-65.
[PubMed Citation] [Order full text from Infotrieve]

15) Viorritto EN, Kureshi SA, Owens JA
Narcolepsy in the pediatric population.
Curr Neurol Neurosci Rep. 2012 Apr;12(2):175-81.
Narcolepsy is characterized by excessive daytime sleepiness, with or without cataplexy. Associated features include sleep paralysis, hypnagogic or hypnopompic hallucinations, and disturbed nocturnal sleep. Narcolepsy is strongly associated with the HLA DQB1*0602 allele, and its symptoms stem from destruction of hypocretin-secreting neurons in the hypothalamus. Recently identified autoantibodies to Tribbles homologue 2 in some patients, as well as cases associated with H1N1 vaccination, support an autoimmune mechanism. There are many challenges in diagnosing and treating pediatric narcolepsy. Caution must also be used in interpreting polysomnography and multiple sleep latency test results in children. HLA testing is nonspecific, and no commercial test exists to measure cerebrospinal fluid hypocretin levels. Neuroimaging has not yet proven useful in primary narcolepsy. Treatment of sleepiness and cataplexy in children requires extrapolating from adult studies. Hopefully, further insights into the pathophysiology of narcolepsy will allow for new therapeutics to manage the symptoms and modify the course of the disease. [PubMed Citation] [Order full text from Infotrieve]

16) Han F, Lin L, Li J, Aran A, Dong SX, An P, Zhao L, Li QY, Yan H, Wang JS, Gao HY, Li M, Gao ZC, Strohl KP, Mignot E
TCRA, P2RY11, and CPT1B/CHKB associations in Chinese narcolepsy.
Sleep Med. 2012 Mar;13(3):269-72.
[PubMed Citation] [Order full text from Infotrieve]

17) Tupone D, Madden CJ, Cano G, Morrison SF
An orexinergic projection from perifornical hypothalamus to raphe pallidus increases rat brown adipose tissue thermogenesis.
J Neurosci. 2011 Nov 2;31(44):15944-55.
Orexin (hypocretin) neurons, located exclusively in the PeF-LH, which includes the perifornical area (PeF), the lateral hypothalamus (LH), and lateral portions of the medial hypothalamus, have widespread projections and influence many physiological functions, including the autonomic regulation of body temperature and energy metabolism. Narcolepsy is characterized by the loss of orexin neurons and by disrupted sleep, but also by dysregulation of body temperature and by a strong tendency for obesity. Heat production (thermogenesis) in brown adipose tissue (BAT) contributes to the maintenance of body temperature and, through energy consumption, to body weight regulation. We identified a neural substrate for the influence of orexin neurons on BAT thermogenesis in rat. Nanoinjection of orexin-A (12 pmol) into the rostral raphe pallidus (rRPa), the site of BAT sympathetic premotor neurons, produced large, sustained increases in BAT sympathetic outflow and in BAT thermogenesis. Activation of neurons in the PeF-LH also enhanced BAT thermogenesis over a long time course. Combining viral retrograde tracing from BAT, or cholera toxin subunit b tracing from rRPa, with orexin immunohistochemistry revealed synaptic connections to BAT from orexin neurons in PeF-LH and from rRPa neurons with closely apposed, varicose orexin fibers, as well as a direct, orexinergic projection from PeF-LH to rRPa. These results indicate a potent modulation of BAT thermogenesis by orexin released from the terminals of orexin neurons in PeF-LH directly into the rRPa and provide a potential mechanism contributing to the disrupted regulation of body temperature and energy metabolism in the absence of orexin. [PubMed Citation] [Order full text from Infotrieve]

18) Church GM
New technologies for integrating genomic, environmental and trait data.
J Clin Sleep Med. 2011 Oct 15;7(5 Suppl):S43-4.
Rare diseases, which (by definition) occur at a frequency less than 1/2000 per allele - are individually rare, yet common collectively (10% affected and 50% carrier rates). There are 1800 genes which have tests considered highly predictive and actionable. Human genes with known variants causing insomnia, narcolepsy, and circadian variation include Prion Protein Fatal Familial Insomnia (PRNP), hypocretin (HCRT), DQ beta 1 (DQB1), and period circadian protein homolog (PER2). We have developed human genome sequencing technology that lowered costs a million-fold over the past 6 yr. This has increasingly enabled the use of the causative alleles above, which are far more valuable than merely correlated or common variants. To expand this further we have established community resources for open access collection, integration and interpretation of diverse personal genomic, environmental and trait data [PubMed Citation] [Order full text from Infotrieve]

19) Kornum BR, Faraco J, Mignot E
Narcolepsy with hypocretin/orexin deficiency, infections and autoimmunity of the brain.
Curr Opin Neurobiol. 2011 Dec;21(6):897-903.
The loss of hypothalamic hypocretin/orexin (hcrt) producing neurons causes narcolepsy with cataplexy. An autoimmune basis for the disease has long been suspected and recent results have greatly strengthened this hypothesis. Narcolepsy with hcrt deficiency is now known to be associated with a Human Leukocyte Antigen (HLA) and T-cell receptor (TCR) polymorphisms, suggesting that an autoimmune process targets a single peptide unique to hcrt-cells via specific HLA-peptide-TCR interactions. Recent data have shown a robust seasonality of disease onset in children and associations with Streptococcus Pyogenes, and influenza A H1N1-infection and H1N1-vaccination, pointing towards processes such as molecular mimicry or bystander activation as crucial for disease development. We speculate that upper airway infections may be common precipitants of a whole host of CNS autoimmune complications including narcolepsy. [PubMed Citation] [Order full text from Infotrieve]

20) Hor H, Bartesaghi L, Kutalik Z, Vicário JL, de Andrés C, Pfister C, Lammers GJ, Guex N, Chrast R, Tafti M, Peraita-Adrados R
A missense mutation in myelin oligodendrocyte glycoprotein as a cause of familial narcolepsy with cataplexy.
Am J Hum Genet. 2011 Sep 9;89(3):474-9.
Narcolepsy is a rare sleep disorder characterized by excessive daytime sleepiness and cataplexy. Familial narcolepsy accounts for less than 10% of all narcolepsy cases. However, documented multiplex families are very rare and causative mutations have not been identified to date. To identify a causative mutation in familial narcolepsy, we performed linkage analysis in the largest ever reported family, which has 12 affected members, and sequenced coding regions of the genome (exome sequencing) of three affected members with narcolepsy and cataplexy. [PubMed Citation] [Order full text from Infotrieve]