It has been evidenced by a domestic population-based cohort study that six obesity-related genes, including fat mass and obesity-associated protein (FTO), melanocortin-4 receptor (MC4R), mitogen-activated protein kinase 5 (MAP2K5), glucosamine-6-phosphate deaminase 2 (GNPDA2), proprotein convertase subtilisin/kexin type 1 (PCSK1), and brain-derived neurotrophic factor (BDNF), were strongly associated with sleep duration, increased leptin levels, and the risk of childhood obesity [55]. Here, MC4R is linked to obesity due to melanocortin 4 receptor deficiency.