XRCC1 and xeroderma pigmentosum-Cockayne syndrome complex: For example, variants of genes involved in DNA repair, such as x-ray repair cross complementing 1 (XRCC1), XRCC3, human 8-oxoguanine DNA N-glycosylase 1 (hOGG1), and xeroderma pigmentosum group D (XPD), have been documented in schizophrenia pathophysiology [2].