Genetic markers in narcolepsy.

Narcolepsy has long been known to have a hereditary familial basis. All of 37 patients with narcolepsy expressed the major histocompatibility complex antigen HLA DR2 compared with 21.5% of 200 normal controls. This finding confirms the genetic basis for the disease, and furthermore links it with the short arm of chromosome 6. If the sleep disturbance in narcolepsy is due to a gene-determined defect in a neurotransmitter or receptor factor, the responsible agent may be DR2 itself or an enzyme determinant linked to DR2. This is the strongest HLA-disease association so far discovered.