Some studies found that the threonine-to-methionine substitution at codon 241 of the XRCC3 gene (T241M) was associated with radiosensitivity in non-cancer subjects but did not cause significant difference in DNA repair capacity between the variant and wild-type genotypes [27], [28], while the glutamine-to-glutamic acid substitution at codon 185 of NBN gene (E185Q) may influence the interaction between NBN and BRCA1 proteins responsible for recognition and repair of aberrant DNA [29], [30]. Here, XRCC3 is linked to cancer.