The Interplay of the CRY1 and PER2 Genes in the Modulation of Chronotype
Anfal A. AbuHilal
Mohmmad M. Herzallah
Al-Quds University, Deanship of Scientific Research
Background: Prior studies investigated the role of the negative feedback loop within the suprachiasmatic nucleus on modulating the circadian rhythm. The regulation of the circadian rhythm is modulated by the synchronization of the endogenous system with the environmental cues including light and temperature. Variations in clock genes between individuals can produce different chronotypes (morningness and eveningness). The cryptochrome gene (CRY1) and period gene (PER2) genes have an inhibitory effect on the negative feedback loop. The c.1657+3A>C CRY1 polymorphism causes a gain of function mutation leading to the lengthening of the chronotype (late chronotype). Meanwhile, PER2 polymorphism (G3853A) has been associated with diurnal performances and the early chronotype.