ABCA1 and Alzheimer disease: None of the SNPs analysed alone exhibited an impact on AD incidence, yet the risk was significantly greater among wild-type homozygotes of rs3931914 expressing either ABCA1 (cholesterol transporter gene) polymorphisms: rs1800977 (OR = 2.77; p = 0.02) or rs2422493 (OR = 2.07; p = 0.02).