Single nucleotide polymorphisms in base-excision repair genes hOGG1, APE1 and XRCC1 do not alter risk of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a poorly understood etiology. There is considerable evidence that oxidative stress occurs in AD and increased DNA damage has been found in brain tissues and leukocytes of AD patients. Base excision repair (BER) is the major pathway responsible for removing oxidative DNA damage. Polymorphisms in DNA-repair genes have been associated with the increased risk of several age-related disorders including various types of cancer and could also be related to the etiology of AD. We conducted a case-control study including 91 patients with AD and age- and sex-matched 93 control subjects to examine the role of single nucleotide polymorphisms of BER genes, hOGG1 (Ser326Cys), APE1 (Asp148Glu) and XRCC1 (Arg280His and Arg399Gln) as a risk factor for AD. The frequencies of the hOGG1-Ser326Cys, APE1-Asp148Glu and XRCC1-Arg280His and XRCC1-Arg399Gln variant alleles in our control group were 0.23, 0.31, 0.10 and 0.33, respectively. No significant association was observed between the variant alleles of hOGG1-Ser326Cys (OR = 1.32, 95% CI = 0.83–2.11), APE1-Asp148Glu (OR = 1.08, 95% CI = 0.70–1.68), XRCC1-Arg280His (OR = 0.53, 95% CI = 0.24–1.14) and XRCC1-Arg399Gln (OR = 1.05, 95% CI = 0.68–1.63) and AD. Our results suggest that the polymorphic variants of these BER genes are not independent risk factors for AD.