DNA repair gene XRCC1 and XPD polymorphisms and the risk of idiopathic azoospermia in a Chinese population

Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity and further influence the risk of developing cancer. However, little information is available on these polymorphisms in infertility. To investigate whether polymorphisms in DNA repair genes, X-ray repair cross-complementing group 1 (XRCC1) and xeroderma pigmentosum group D (XPD), alone or in combination, are associated with the risk of developing idiopathic azoospermia, the genotype and allele frequencies of three observed polymorphisms (XRCC1 Argl94Trp and Arg399GIn, and XPD Lys751G1n) were examined by polymerase chain reaction-restriction fragment length polymorphism based on a Chinese population consisting of 171 idiopathic azoospermia patients and 247 normal-spermatogenesis fertile controls. Associations between the polymorphisms and the idiopathic azoospermia risk were estimated by logistic regression, and the Statistical analysis system was used to test the gene-gene joint effects. All observed polymorphisms were in agreement with Hardy-Weinberg equilibrium. The XPD 751G1n allele seemed to be a risk allele for azoospermia, with a frequency of 11.40% in the cases and 5.67% in the controls (p=0.004). Compared with the Lys/Lys genotype, the XPD 751 Lys/ Gln+Gln/Gln genotype was associated with a moderately increased risk of azoospermia (OR=2.09), while the risk increased 5.100- or 3.064-fold, respectively, when combined with the XRCC1 194 Arg/Arg or 399 Arg/Arg genotype. In conclusion, our study provided the first evidence that the XPD and XRCC1 polymorphisms contributed to the risk of developing idiopathic azoospermia in a selected Chinese population.