In addition, studies correlating single nucleotide polymorphisms (SNPs) in the 3′ untranslated region (UTR) of the FGF21 gene with metabolic syndrome, obesity, and diabetes showed that genetic variants in the 3′ UTR region of the FGF21 gene were associated with obesity and not with metabolic syndrome and diabetes [39]. This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.