XRCC6 and male infertility: Among several genetic variants of the XRCC5, XRCC6, and XRCC7, a novel variable number of tandem repeats (VNTR) in the promoter region of XRCC5 and two single nucleotide polymorphisms (SNPs) XRCC6 -61C>G and XRCC7 6721G>T located in the promoter region of XRCC6 and intron 8 of XRCC7 genes, respectively, have been extensively studied in various disorders such as cancer [22–29] and autoimmune diseases [30, 31], but whether genetic variants in these repair pathway genes affect susceptibility to male infertility remains unknown.