[Association between angiotensin-converting enzyme gene polymorphism and Alzheimer's disease]

To determine the association between the polymorphism of angiotensin converting enzyme (ACE) gene and Alzheimer's disease (AD).

This case-control study involved 201 AD patients and 257 healthy subjects matched for age and gender as the control group. Polymerase chain reaction amplification and matrix-assisted laser desorption/ ionization time of flight mass spectrometry were used to examine the rs4291, rs4309, and rs4343 of ACE gene, and the difference in genotypes, allelotype frequencies and haplotype frequencies were analyzed between the two groups.

No statistic difference was found in the genotype and allelotype frequencies of rs4291 locus between AD and control groups (P>0.05). A significant difference was found in the genotype and allelotype frequencies of rs4309 between the two groups with a significant increase in the C allelotype frequency in AD group (OR=1.917, 95% CI=1.431-2.568, P<0.05). The difference in the genotype frequency of rs4343 was not significant between the two groups, but the allelotype frequencies differed significantly with a decreased A allelotype frequency in AD group(OR=0.714, 95% CI=0.532-0.957, P=0.024). Analysis of the linkage disequilibrium among the loci of rs4291, rs4309 and rs4343 showed a D' all above 0.65 between one another. Haplotype analysis confirmed the existence of 5 haplotypes, namely ATA, ACA, TCA, TCG and TTG, indicating a negative correlation between haplotype ATA and AD occurrence (OR=0.558, 95% CI=0.420-0.741, P<0.05) and positive correlations of haplotype ACA and TCA with AD occurrence (ACA: OR=4.883, 95% CI=2.267-10.518, P<0.05; TCA: OR=2.269, 95% CI=1.083-4.754, P<0.05).

The polymorphism of rs4291 may have no relation with the incidence of AD. Polymorphisms of s4309 and rs4343 may be related to AD, and ATA, ACA and TCA haplotypes composed of rs4291/rs4309/rs4343 may be related to AD.