Loss of hypocretin-producing neurons, possibly of autoimmune origin, is the core disease mechanism of narcolepsy type 1, whereas the pathophysiology of narcolepsy type 2 is poorly understood.121 It is estimated that about 25 to 50 cases of narcolepsy occur per 100 000 individuals, with a higher prevalence of narcolepsy type 2.122,123. The gene discussed is HCRT; the disease is narcolepsy.