MC4R and obesity due to melanocortin 4 receptor deficiency: In a genetic association study conducted by a British group on the data of approximately 0.5 million people available from UK Biobank that focused on 61 nonsynonymous variants found in MC4R, they identified a subset of individuals as carriers for gain-of-function alleles exhibiting lower BMI and obesity, type 2 diabetes, and coronary artery disease9.