FFAR4 and obesity due to melanocortin 4 receptor deficiency: In the present study, 13 well-known obesity-related genes, including leptin receptor (LEPR), proopiomelanocortin (POMC), melanocortin 4 receptor (MC4R), transmembrane protein 18 (TMEM18), potassium channel tetramerization domain containing 15 (KCTD15), glucosamine-6-phosphate deaminase 2 (GNPDA2), SH2B adapter protein 1 (SH2B1), mitochondrial carrier homolog 2 (MTCH2), neuronal growth regulator 1 (NEGR1), fat mass and obesity-associated protein (FTO), leptin (LEP), proprotein convertase 1 (PCSK1), and G-protein coupled receptor 120 (GPR120) [20–23], were studied.