MC4R and obesity due to melanocortin 4 receptor deficiency: In 2008, the genome-wide association studies (GWAS) reported that rs17782313 single nucleotide polymorphism (SNP) mapped 188 kb downstream of the melanocortin 4 receptor (MC4R) gene was strongly associated with body mass index (BMI) and risk of obesity in European populations.[1] Furthermore, subsequent studies have confirmed the positive association between SNPs in/near the MC4R gene and risk of obesity in populations with different races/ethnicities.[2–4]