Polymorphism in DNMT1 may modify the susceptibility to oligospermia

As an important methyltransferase, DNMT1 plays a key role in DNA methylation that is essential for normal spermatogenesis, which suggests that it may be involved in male infertility with spermatogenesis impairment. To explore the relationship between DNMT1 and spermatogenesis impairment, polymorphic distributions of single-nucleotide polymorphisms (SNP) rs16999593, rs2228612 and rs2228611 in DNMT1 were investigated in 342 infertile patients with idiopathic azoospermia or oligospermia and 232 fertile controls in a Chinese population. As a result, no significant differences in allele and genotype frequencies of the three SNP between total patients and controls were observed. However, after stratifying the patients, significant differences in allele and genotype frequencies were detected between oligospermia subgroup and control group. The frequencies of rs16999593 allele A (83.6% versus 77.6%, P=0.033) and genotype AA (69.2% versus 59.0%, P=0.037) and SNP rs2228611 genotype AA (18.4% versus 9.9%, P=0.016) in patients with oligospermia were significantly higher than those in control group. These findings suggest that the polymorphism in DNMT1 might be associated with oligospermia and could modify the susceptibility of oligospermia.