Narcolepsy-Associated HLA Class I Alleles Implicate Cell-Mediated Cytotoxicity

Area of Science:

• Immunogenetics
• Neuroimmunology
• Sleep Medicine

Background:

• Narcolepsy with cataplexy is strongly associated with HLA class II DQB1*06:02.
• While HLA class II genes contribute to narcolepsy susceptibility, the effector immune cells remain unclear.
• Hypocretin neuron loss, potentially due to autoimmunity, is implicated in narcolepsy pathogenesis.

Purpose of the Study:

• Investigate the role of HLA class I genes in narcolepsy susceptibility.
• Explore potential CD8+ T-cell involvement in narcolepsy pathogenesis.
• Identify specific HLA class I alleles and amino acid residues associated with narcolepsy risk.

Main Methods:

• Genotyping of HLA class I (A, B, C) and class II (DQB1) alleles in 944 narcolepsy with cataplexy patients and 4,043 controls.
• All subjects were DQB1*06:02 positive.
• Association analyses conditioned on DQB1 alleles were performed.

Main Results:

• HLA-A*11:01, C*04:01, and B*35:01 alleles showed significant association with narcolepsy susceptibility.
• Specific amino acid residues in HLA-A (Tyr9) and HLA-C (Ser11) demonstrated even stronger associations.
• Odds ratios ranged from 1.34 to 1.49 for associated alleles and 1.32 to 1.34 for amino acid residues.

Conclusions:

• Findings suggest a genetic predisposition to narcolepsy involving HLA class I, potentially through infectious triggers or immune cytotoxic mechanisms.
• The results support a role for HLA class I-restricted CD8+ T-cells in targeting hypocretin neurons in narcolepsy.
• This study provides a genetic framework for understanding narcolepsy autoimmunity.