CHKB and narcolepsy: Subjects possessing the risk allele of the susceptibility SNP showed significantly lower levels of mRNA expression of both CPT1B and CHKB. We also observed that narcolepsy patients show abnormally low levels of carnitine [24], on which CPT1B (carnitine palmitoyltransferase 1B) is relevant, and that carnitine improves the sleep of the patients [25].