Rs669

rs669 is a SNP in the alpha-2-macroglobulin A2M gene. In dbSNP orientation, the rs669(A) allele encodes an isoleucine, and the rs669(G) allele encodes a valine; the SNP is also known as the Ile/Val variant.

On its own, rs669 was not seen to reproducibly and independently increase risk for Alzheimer's disease in several studies of ~200 Italian patients. However, the T-C-A haplotype of rs12316150-rs1050283-rs669 was associated with both early- and late-onset Alzheimer's disease. The majority of the disease risk from this haplotype was based on rs1050283.

The original 2004 study of 148 Italian sporadic AD patients yielded an odds ratio for the rs669(G;G) genotype (as oriented in dbSNP orientation) of 3.81 (CI: 1.66-8.75). The presence of rs2333227(C;C), in addition to rs669(G;G), appears to synergistically increase the risk of AD to an odds ratio of 25.5 (CI: 4.65-139.75), regardless of ApoE status.