ABCA1 rs2230805 and rs2230806 common gene variants are associated with Alzheimer's disease

The ATP-binding cassette, sub-family A, member 1 gene (ABCA1) is a relevant positional and functional candidate gene for Alzheimer's disease (AD). A case-control association study of genetic variations covering the ABCA1 locus was performed in relation to AD risk in a Hungarian sample. Five single nucleotide polymorphisms (rs2422493: C-477T, rs2740483: G-17C, rs2230805: G474A/L158L, rs2230806: G656A/R219 K and rs2066718: G2311A/V771 M) were genotyped in 431 AD patients and 302 cognitively healthy, elderly controls. In single marker analysis, significant associations were found in the case of rs2230805 and rs2230806 polymorphisms: the minor A allele containing genotypes for both polymorphisms were more frequent in the control compared to the AD group. Haplotype analysis revealed that rs2230805, rs2230806 and rs2066718 polymorphisms created a linkage disequilibrium (LD) block with a strong LD between rs2230805 and rs2230806 polymorphisms. In the haplotype risk association tests, A-A-G haplotype of the rs2230805-rs2230806-rs2066718 polymorphisms was found to be nominally significantly more frequent in the control group. After correcting p values for multiple testing, only the effects of the rs2230805 and rs2230806 polymorphisms remained significant in the recessive model suggesting a modest protective effect of their minor alleles in AD, which should be interpreted with considerable caution, until further studies elucidate their role in AD pathology.