NARCOLEPSY-CATAPLEXY, A DISEASE CAUSED BY THE LOSS OF ∼70,000 HYPOCRETIN CELLS IN THE HYPOTHALAMUS AFFECTS ∼20 PER 100,000 INDIVIDUALS, with an incidence of ∼ 0.3–0.6 per 100,000 person-years.
1,2 Onset is most typically in the teens, and cases with onset before age 6 or after 40 are rare in Western Europe and North America.
3 The disease is extremely tightly associated with human leukocyte antigen (HLA) DQB1*0602
4, so that DQB1*0602 negative cases without documented loss of hypocretin cells, as measured by cerebrospinal fluid (CSF) hypocretin levels, are exceptional; only 5 such cases have been reported in the literature. The cause of narcolepsy is likely autoimmune based on the HLA association, association with T-cell receptor polymorphisms,
5 and recently reported Tribbles 2 autoantibodies.
6