PER1 and obesity due to melanocortin 4 receptor deficiency: From a non-tumor perspective, PER1 is related to conditions such as Parkinson's disease, obesity, sleep, drug resistance, and premature ovarian insufficiency (Zheng et al., 2019; Delgado-Lara et al., 2020; EmeklI et al., 2020; Mabrouk et al., 2020; Arellanes-Licea et al., 2021).