No abstract

Narcolepsy is a rare sleep disorder with the strongest human leukocyte antigen (HLA) association ever reported. Since the associated HLA-DRB1*1501-DQB1*0602 haplotype is common in the general population (15-25%), it has been suggested that it is almost necessary but not sufficient for developing narcolepsy. To further define the genetic basis of narcolepsy risk, we performed a genome-wide association study (GWAS) in 562 European individuals with narcolepsy (cases) and 702 ethnically matched controls, with independent replication in 370 cases and 495 controls, all heterozygous for DRB1*1501-DQB1*0602. We found association with a protective variant near HLA-DQA2 (rs2858884; P < 3 x 10(-8)). Further analysis revealed that rs2858884 is strongly linked to DRB1*03-DQB1*02 (P < 4 x 10(-43)) and DRB1*1301-DQB1*0603 (P < 3 x 10(-7)). Cases almost never carried a trans DRB1*1301-DQB1*0603 haplotype (odds ratio = 0.02; P < 6 x 10(-14)). This unexpected protective HLA haplotype suggests a virtually causal involvement of the HLA region in narcolepsy susceptibility.

An overwhelming portion of genetic risk for narcolepsy with cataplexy is found at DQB1 locus. Since DQB1*06:02 positive subjects are at 251-fold increase in risk for narcolepsy, and all recent cases of narcolepsy after H1N1 vaccination are positive for this allele, DQB1 genotyping may be relevant to public health policy.

. CC-BY 4.0 International license It is made available under a was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint (which . http://dx.doi.org/10.1101/373555 doi: bioRxiv preprint first posted online Jul. 22, 2018; Main Text 1 Type 1 narcolepsy (T1N) is a sleep disorder that affects 1/3,000 individuals across ethnic 2 groups 1-3 . Onset is typically in childhood through early adulthood. Symptoms are caused by the 3 destruction of hypocretin/orexin neurons, a small neuronal subpopulation of the hypothalamus 4 . 4Although the disease is considered autoimmune, the exact mechanism leading to hypocretin cell 5 death is still unclear. Indeed, T1N is strongly associated with alleles encoding the heterodimer 6 DQ0602 haplotype (HLA-DQA1*01:02~DQB1*06:02, 97% vs. 25%) across ethnic groups 5,6 . 7Other loci previously associated with the disease include T cell receptor (TCR) loci alpha (TRA) 8 and beta (TRB), receptors of HLA-peptide presentations, and other autoimmune associated 9 genes (CTSH, P2RY11, ZNF365, IFNAR1 and TNFSF4) [7][8][9][10] . 11Triggers of T1N point to the immune system, including influenza and Streptococcus Pyogenes 12 infections 9,11,12 , as well as immunization with Pandemrix®, an influenza-A vaccine developed 13 specifically against the H1N1 "swine flu" strain 13-20 suggest a strong environmental modifier of 14 disease risk for narcolepsy. Increased T1N incidence following the Pandemrix® vaccination was 15 first seen in Northern Europe [13][14][15][16][17][18][19][20] with 8-fold increase in incidence in (0.79/100,000 to 16 6.3/100,000) in children. The specificity was striking, as increased T1N was later detected in all 17 countries where Pandemrix® was used, whereas countries using other pH1N1 vaccine brands 18 did not detect vaccination-associated increases in incidence [13][14][15][16][17][18][19][20][21][22] . is defined by antigen presentation, mediated through specific T cell receptor chains, and 27 modulated by influenza-A as a critical trigger. 28. CC-BY 4.0 International license It is made available under a was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint (which . http://dx.doi.org/10.1101/373555 doi: bioRxiv preprint first posted online Jul. 22, 2018; examined using LD Score Regression 33 , the shared heritability was largest with type-1 diabetes Genetics of vaccination-triggered narcolepsy. We have previously shown that both influenza 21 infections and, in rare cases, immunization with Pandemrix® can trigger narcolepsy 13,18,19,42,43 . 22The baseline for narcolepsy in unvaccinated vs. Pandemrix® vaccinated individuals was 23 0.7/100,000 vs. 9/100,000 person years with on average 10-fold increase in risk 13,18,19,[42][43][44] was not peer-reviewed) is t...

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.