Since the Ku protein, Ku70 (XRCC6)/80 (XRCC5), and DNA-PKcs (XRCC7) as critical components of NHEJ play important role in DNA integrity of spermatogenesis and can affect the offspring, we hypothesize that genetic variation of these genes may contribute to male infertility risk. This evidence concerns the gene XRCC6 and male infertility.