While the ApoE4 allele (rs429358(C)) is widely accepted as the predominant genetic risk factor for Alzheimer's disease, there are likely to be numerous other factors, both genetic and environmental, associated to lesser degrees with susceptibility to the disease. Genes influencing the immune system, and in particular susceptibility to viral infections such as herpes, may be among such factors. [HSV-1 viruses, is seen more commonly in ~300 Alzheimer patients than in the same number of controls. The risk allele is rs241448(C). The odds ratio is reported to be 2.14 (CI: 1.02-2.55) for rsrs241448(C;C) homozygotes, and 1.51 (CI: 0.80-1.93) for rsrs241448(C;T) heterozygotes, compared with rsrs241448(T;T) homozygotes. This may be particularly significant for carriers of ApoE4 alleles. [PMID 17420072]
[PMID 19680542] Tissue effect on genetic control of transcript isoform variation.