Conversely, only 10–20% of patients withnarcolepsy without cataplexy have low CSF HCRT-1 levels at diagnosis.2,3 A brain study of two patients with narcolepsy without cataplexy showedpartial loss of hypocretin neurons, suggesting that the presence of cataplexy in narcolepsycould be linked to the severity of hypocretin neuron loss.4 In children with NT1, disease onset is often rapid anddramatic, with the full clinical picture of excessive daytime sleepiness (EDS) and cataplexyoccurring within several days.5Conversely, a progressive appearance of NT1 symptoms is frequent in adults. The gene discussed is HCRT; the disease is narcolepsy.