Annals of medicine
-
Multiple lines of evidence suggest that the circadian clock contributes to the pathogenesis of winter depression or seasonal affective disorder (SAD). We hypothesized that sequence variations in three genes, including Per2, Arntl, and Npas2, which form a functional unit at the core of the circadian clock, predispose to winter depression. ⋯ Variations in the three circadian clock genes Per2, Arntl, and Npas2 are associated with the disease, supporting the hypothesis that the circadian clock mechanisms contribute to winter depression.