HLA DR2 in narcolepsy with sleep-onset REM periods but not cataplexy.

To determine the association of HLA DR2 in patients with narcolepsy without cataplexy, a case-control study was performed. Patients receiving the diagnosis of narcolepsy without cataplexy had excessive daytime sleepiness (EDS) and polysomnographic findings consistent with narcolepsy but no clinical evidence of cataplexy. Of 28 patients identified, 12 agreed to return for HLA typing. Respondents did not differ from nonrespondents in demographic, clinical, or sleep laboratory data. The comparison group was 503 individuals, those 30 years and older, on the Michigan Kidney Transplant Registry. The odds ratio obtained from logistic regression indicated a strong association between narcolepsy without cataplexy and HLA DR2. To control for potential confounding variables, multivariate models were constructed to explore the joint effects of HLA DR2 and each one of the covariates (age, sex, and race), their possible combinations, and the effect of all three covariates. The odds ratios decreased minimally and the association between the disease and HLA DR2 remained significant.