Although the mechanism of most genetic loci predispose individuals to obesity is not clear so far, evidence indicated that they were involved in energy uptake (FTO, MC4R, PCSK1, and BDNF) and adipocyte differentiation (FTO, TMEM18, BDNF, MTCH2 and NEGR1) [32]–[35]. The gene discussed is MC4R; the disease is obesity due to melanocortin 4 receptor deficiency.