We previously reported that a single nucleotide polymorphism (SNP) associated with obesity (FTO rs9939609-A) was inversely associated with low-grade prostate cancer (odds ratio, OR 0.90 per A allele; 95 % CI 0.81, 0.99; p = 0.03), but positively associated with high-grade cancer (OR 1.16; 0.99, 1.37; p = 0.07) [15]. Here, FTO is linked to obesity due to melanocortin 4 receptor deficiency.