Amyloid peptide is thought to play a critical role in neuronal death in Alzheimer's disease (AD), most likely through oxidative stress. Free radical-related injury leads to DNA breaks, which subsequently activates the repair enzyme poly(ADP-ribose) polymerase-1 (PARP-1). In this study, the relationship between genetic variants situated at the PARP-1 gene and AD development was investigated. We performed a case and control study from a Taiwanese population enrolled 120 AD patients and 111 healthy controls by using a polymerase chain reaction restriction fragment length polymorphism approach for two PARP-1 exonic polymorphisms, 414C/T (rs1805404) and 2456T/C (rs1136410), corresponding to protein residues at positions 81Asp/Asp and 762Val/Ala. There were no significant differences in allele or genotype frequencies for either PARP-1 gene variant between the case and control groups; however, upon analysis of the haplotype distribution, four haplotypes (Hts) were identified. We found that the distributions of Ht3-TT and Ht4-CC were significantly associated with an increased risk of AD (P<0.0001), whereas the Ht1-TC haplotype showed a protective effect for cases compared with the control group (P<0.05). These results reveal that the PARP-1 gene is highly associated with AD susceptibility and might contribute to a critical mechanism that mediates cell survival or death as a response to cytotoxic stress.

Background: The administration of memantine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has clinically improved the cognitive function of patients with Alzheimer’s disease (AD), indicating that a disturbance in glutamatergic transmission might be involved in a predisposition to developing the disease. Aim: The potential association of polymorphisms in NMDA receptor subunits NR3A and NR3B, encoded by the GRIN3A and GRIN3B genes, with AD was investigated. Methods: We performed a case-control study. Two single nucleotide polymorphisms, 3104 G/A (rs10989563) and 3723 G/A (rs3739722), in the GRIN3A gene and 2 GRIN3B gene polymorphisms, 1210 C/T (rs4807399) and 1730 C/T (rs2240158), were studied. Results: Upon genotyping of the exonic polymorphism in the GRIN3A gene, the G allele was present at a higher rate than the A allele at position 3723 in AD patients compared with normal groups (p < 0.05). Three haplotypes (designated Ht1–3) were identified from these 2 polymorphisms (3104 G/A and 3723 G/A), and the distribution of Ht2 (AG) differed between AD patients and controls (p < 0.05). Additionally, from the 2 GRIN3B gene variants 1210 C/T and 1730 C/T analyzed, no strong association with AD was observed. Conclusion: These observations suggest that the genetic variation of the NR3A, but not NR3B, subunit of the NMDA receptor may be a risk factor for AD pathogenesis among the Taiwanese population.