ABCB1 and Alzheimer disease: Although ABCB1 gene variants such as 3435C > T (rs1045642), 2677G > T/A (rs2032582), 1236C > T (rs1128503) polymorphisms have been reported to be associated with AD risk23, 24, 26, several researchers have shown opposite results25, 27, 28, 29, 30, 31.