The neuroexcitatory peptide hypocretin and its receptors are central to the
pathophysiology of both human and animal models of the disease. In this st
udy of American and Icelandic patients with narcolepsy, the authors found n
o significant association between narcolepsy and single-nucleotide polymorp
hisms in the genes for hypocretin or its two known receptors, hypocretin re
ceptor-1 and hypocretin receptor-2.