HCRTR2 and narcolepsy: Canines with narcolepsy were found to have a mutation in the orexin-2 (hypocretin-2) receptor (Lin et al., 1999) while mice lacking the orexin peptide (Chemelli et al., 1999) or the neurons containing orexin (hypocretin) (Hara et al., 2001) displayed behavioral and EEG signs of narcolepsy.