MC4R and obesity due to melanocortin 4 receptor deficiency: Additional studies by Castro et al. on four obesity-related genes (PPARG-rs1801282; PPARGC1A-rs8192678; FTO-rs9939609; MC4R-rs17782313) showed that three of the four genes (PPARG, FTO, MC4R) had a combined effect on overweight and obesity at an odds ratio of 1.65 (p = 0.008) in a large case-control study in the Brazilian population [28].