The 825 T allele of the GNB3 gene is associated with an increased BMI across different ethnicities, and apparently represents a "thrifty genotype".20,21 Several studies,20,21,28,37,39 have reported a significant relationship between the GNB3 825C/T polymorphism and obesity or fat metabolism. The gene discussed is GNB3; the disease is obesity due to melanocortin 4 receptor deficiency.