DNMT1 and male infertility: In summary, in this case-control study, we found that the carrier of DNMT1 CA genotype had a significantly increased risk of idiopathic male infertility compared with DNMT1 CC genotype carriers, although no significant difference was found in DNMT3A and DNMT3L. Our results support the hypothesis that DNMT1 polymorphism may be associated with an increased risk of idiopathic male infertility in a Han-Chinese population.