Several groups independently reported that the mutation of tryptophan to arginine at position 64 of human ADRβ3 (W64R) shows a strong association with obesity, glucose intolerance, hypertension, dyslipidemia, and early onset of Type 2 diabetes mellitus [26,27,28,29,30,31,32,33,34]. This evidence concerns the gene ADRB3 and obesity due to melanocortin 4 receptor deficiency.