The Polymorphism of the ATP-Binding Cassette Transporter 1 Gene Modulates Alzheimer Disease Risk in Chinese Han Ethnic Population

Abstract

Recent studies highlight a potential role of cholesterol metabolic disturbance in the pathophysiology of Alzheimer disease (AD). The adenosine triphosphate (ATP)-binding cassette transporter 1 (ABCA1) gene resides within proximity of linkage peaks on chromosome 9q influence AD and plays a key role in cellular cholesterol efflux in the brain. We studied the role of R219K and V825I polymorphisms of ABCA1 in modulating the risk of AD in 321 AD patients and 349 comparisons of Chinese Han. Genotyping of R219K and V825I were performed by PCR-restriction fragment length polymorphism analysis. The genotype distribution of R219K was different with more RK in total AD group (χ(2) = 8.705, df = 2, p = 0.013), late-onset AD (LOAD) group (χ(2) = 10.636, df = 2, p = 0.005), APOE non-ε4ε4 group (χ(2) = 9.900, df = 2, p = 0.007), and female AD group (χ(2) = 8.369, df = 2, p = 0.015). Logistic regression manifested the risk of AD increased in RK carriers in total AD group (Wald = 6.102, df = 1, p = 0.014, odds ratio [OR]: 1.546, 95% confidence interval [95% CI]: 1.094-2.185), LOAD group (Wald = 7.746, df = 1, p = 0.005, OR: 1.921, 95% CI: 1.213-3.041), and APOE non-ε4ε4 group (Wald = 6.399, df = 1, p = 0.011, OR: 1.586, 95% CI: 1.109-2.266). K allele (RK + KK) also increased the risk of AD compared with RR allele in LOAD group (Wald = 4.750, df = 1, p = 0.029, OR: 1.619, 95% CI: 1.050-2.497). However, no discrepancy was found in V825I. In R219K, age at onset (AAO) was significantly lower by 4.9 years on average in patients of KK genotype than those of RK in APOE ε4 carrying group and higher by 5.5 years in patients of KK genotype than those of RR in APOE ε4 noncarrying group. In V825I, AAO was diseased by 4.3 years in II genotype compared with VV genotype in APOE ε4 noncarrying group and 3.4 years in APOE ε4ε4 noncarrying group. The results indicated that the RK genotype or K allele (RK + KK) of R219K may relate to the development of AD in the east of China.