New candidate SNPs for genetic association with Alzheimer's disease: a linkage disequilibrium analysis for the FCGRIIB and PILRA genes

BACKGROUND Two new SNPs have been recently associated to Alzheimer's disease in African American populations: FCGRIIB rs1050501 C/T, and PILRA rs1859788 A/G. The risk of Alzheimer's disease in FCGRIIB C and PILRA A allele carriers is three times higher than in non -carriers. However, the association between these and other single nucleotide polymorphisms (SNPs) has not been assessed. METHODS Linkage disequilibrium analysis, with r2= 0.8 as a threshold value, was used to impute new candidate SNPs, on genomic data from both genes in 26 populations worldwide (n= 2504) from the 1000Genomes database. RESULTS Four SNPs (rs13376485, rs3767640, rs3767639 and rs3767641) were linked to rs1050501 and one (rs2405442) to rs1859788 in the whole sample. CONCLUSIONS Five novel SNPs could be associated with Alzheimer's disease susceptibility and play a causal role, even if none of them are exon variants since their potential roles in the regulation of gene expression.