Compared with those with the GG genotype, patients being heterozygous for the A allele in rs2207396 had a significantly increased risk of azoospermia [odds ratio (OR): 3.8; 95% confidence interval: 1.5-9.5; P=0.008], this OR being even higher in the subgroup treated with alkylating drugs (OR: 8.8; 95% confidence interval: 2.1-36; P=0.004).