MC4R and obesity due to melanocortin 4 receptor deficiency: Functional mutations in the MC4R gene are reportedly associated with hyperphagia, early-onset obesity and hyperinsulinaemia, while polymorphisms near the MC4R gene are linked to increased body mass index (BMI) and abdominal girth.21,22 Variants in the FTO gene have been associated with obesity in a genome-wide study,23 and have been shown to predispose to diabetes through an effect on BMI.24