A GWAS study in Danish, Icelandic, Dutch, European Americans, and African American adults has shown that SNPs in the FTO, MC4R, BDNF, and SH2B1 genes are highly associated with obesity risk via modulating leptin secretion to induce leptin resistance in different ethnicities [33,34,35]. Here, MC4R is linked to obesity due to melanocortin 4 receptor deficiency.