Association Between Polymorphisms of DNA Repair Genes and Risk of Schizophrenia

DNA repair gene polymorphisms have recently been implicated as potential pathogenic contributors of mental disorders. The aims of our study were to investigate the participation of nucleotide and base excision repair mechanisms in schizophrenia and to identify novel candidate DNA repair susceptibility genes.

For these purposes, we genotyped apurinic/apyrimidinic endonuclease 1 (APE1), human 8-oxoguanine DNA N-glycosylase 1 (hOGG1), X-ray repair cross-complementation group 1 (XRCC1), XRCC3, xeroderma pigmentosum group D (XPD), and xeroderma pigmentosum group G (XPG) genes in schizophrenia subjects, their healthy relatives, and unrelated healthy controls.

Carriers of XRCC1 glutamine (Gln), XRCC3 threonine (Thr), hOGG1 cysteine (Cys), and XPD lysine (Lys) alleles were significantly more frequent among the cohort of schizophrenia patients than in controls. In contrast, the frequencies of XRCC3 methionine (Met) and XPD Gln allele carriers and hOGG1 serine (Ser)/Ser genotype carriers were higher among controls than in patients, suggesting a possible protective role for these gene variants against schizophrenia. Moreover, healthy relatives had significantly higher frequencies of XRCC3 Thr+ and XPD Lys+ genotypes than unrelated healthy controls. Minor allele frequencies, haplotypes, and overtransmitted alleles of DNA repair genes were also identified.

Our findings support XRCC1, XRCC3, hOGG1, and XPD as risk genes for schizophrenia and suggest that altered DNA repair functions may be involved in schizophrenia pathophysiology.