MC4R and obesity due to melanocortin 4 receptor deficiency: ,22 Notably, the discovery of rs9939609 variant located in the first intron of FTO (fat mass- and obesity-associated) gene that predisposes to diabetes through an effect on body mass index (BMI),23 and the MC4R (melanocortin-4 receptor) genetic variant in common obesity risk,24 were early contributions of OBB data to obesity genetics.