HLA dosage effect in narcolepsy with cataplexy.
Astrid van der Heide1, Willem Verduijn, Geert W Haasnoot
1Department of Neurology and Clinical Neurophysiology, Leiden University Medical Center, PO Box 9600, 2300, Leiden, The Netherlands, a.van_der_heide@lumc.nl.
Immunogenetics
|October 4, 2014
Summary
Narcolepsy with cataplexy risk increases with higher expression of the HLA-DQ0602 dimer. Homozygosity for specific HLA genes, particularly DQA1*01:02 in certain individuals, significantly elevates disease susceptibility.
Area of Science:
- Immunogenetics
- Sleep Medicine
- Neuroscience
Background:
- Narcolepsy with cataplexy is linked to hypocretin neuron loss and the HLA-DQB1*06:02 allele.
- The functional HLA-DQ0602 dimer comprises DQα and DQβ chains, with DQB1*06:02 preferring DQA1*01:02.
- A dosage effect hypothesis suggests increased HLA-DQ0602 dimer expression influences narcolepsy susceptibility.
Purpose of the Study:
- To investigate the impact of HLA-DQ0602 dimer expression levels on narcolepsy susceptibility.
- To determine if homozygosity for specific HLA alleles, particularly DQA1*01:02, influences disease risk in individuals carrying HLA-DQB1*06:02.
Main Methods:
- HLA genotyping of 248 Dutch narcolepsy patients and 1272 Dutch controls, all positive for HLA-DQB1*06:02.
- Analysis focused on HLA-DQB1 and HLA-DQA1*01:02 alleles to assess homozygosity and heterozygosity patterns.
- Statistical analysis, including odds ratios (O.R.), to compare allele frequencies between patients and controls.
Main Results:
- DQB1*06:02-DQA1*01:02 homozygosity was more frequent in narcolepsy patients (O.R. 2.29).
- A significantly higher prevalence of DQA1*01:02 homozygosity was observed in heterozygous HLA-DQB1*06:02 patients compared to controls (O.R. 2.37, p < 0.001).
Conclusions:
- The findings strongly support a direct role of the HLA-DQ molecule, specifically the DQ0602 dimer, in the pathogenesis of narcolepsy with cataplexy.
- Increased expression of the HLA-DQ0602 dimer, particularly due to DQA1*01:02 homozygosity in DQB1*06:02 carriers, is a significant risk factor for narcolepsy.
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