Genetic markers in familial narcolepsy.

We studied three patients in a single family (father and two sons), all with long histories of overwhelming daytime sleepiness, hypnagogic hallucinations and sleep paralysis. Two of the three had a clear history of cataplexy. Multiple sleep latency tests revealed extremely short sleep onset latencies and at least two sleep onset rapid eye movement periods in each patient. Histocompatibility studies were remarkable for negative HLA-DR2 antigens in all three.