MC4R and metabolic disease: Genome-wide association (GWA) studies have so far identified a large number of single nucleotide polymorphisms (SNPs) in different genes associated with susceptibility to obesity and metabolic diseases, including genetic variants in BDNF, FTO, GCK, GCKR, KCNQ1, MC4R, PROX1, UBE2E2, and so on (13–16).