Through genome-wide association studies and next-generation sequencing, approximately 500 obesity-related genes were identified, with mutations in some of these genes, including leptin and its receptor genes, POMC, MC4R, BDNF, prohormone convertase 1, unique homologue 1, and neurotrophic receptor tyrosine kinase type 2, having been reported to cause obesity [144]. Here, BDNF is linked to obesity due to melanocortin 4 receptor deficiency.