Supplementary Material for: Variants of Base Excision Repair Genes <b><i>MUTYH</i></b>, <b><i>PARP1</i></b> and <b><i>XRCC1</i></b> in Alzheimer's Disease Risk

<b><i>Background:</i></b> Many clinical studies have shown that oxidative stress pathways and the efficiency of the oxidative DNA damage base excision repair (BER) system are associated with the pathogenesis of Alzheimer's disease (AD). Reduced BER efficiency may result from polymorphisms of BER-related genes. In the present study, we examine whether single nucleotide polymorphisms (SNPs) of BER genes are associated with increased risk of AD. <b><i>Methods:</i></b> SNP genotyping was carried out on DNA isolated from peripheral blood mononuclear cells obtained from 120 patients with AD and 110 healthy volunteers. Samples were genotyped for the presence of BER-related SNPs, i.e. <i>XRCC1</i>-rs1799782, rs25487; <i>MUTYH</i>-rs3219489, and <i>PARP1</i>-rs1136410. <b><i>Results:</i></b> We found a positive association between AD risk and the presence of G/A genotype variant of the<i> XRCC1</i> rs25487 polymorphism [odds ratio (OR) = 3.762, 95% CI: 1.793-7.891]. The presence of the A/A genotype of this polymorphism reduced the risk of AD (OR = 0.485, 95% CI: 0.271-0.870). In cases of the <i>PARP1 </i>gene rs1136410 polymorphism, we observed that the T/C variant increases (OR = 4.159, 95% CI: 1.978-8.745) while the T/T variant reduces risk (OR = 0.240, 95% CI: 0.114-0.556) of AD. <b><i>Conclusions:</i></b> We conclude that BER gene polymorphisms may play an important role in the etiology of AD. Diagnosing the presence or absence of particular genetic variants may be an important marker of AD. Further research on a larger population is needed. There is also a need to examine polymorphisms of other BER in the context of AD risk.