We found inverse associations of a related SNP in FTO (rs1558902, which is in linkage disequilibrium with rs9939609 at r2 = 0.90) with overall and low-grade prostate cancer risk (individuals with more BMI increasing alleles had a reduced risk of all prostate cancer and low-grade prostate cancer, respectively (OR 0.97; 95 % CI 0.94, 1.00; p = 0.10, and OR 0.95; 95 % CI 0.90, 1.00; p = 0.06). Here, FTO is linked to Familial prostate cancer.