APOE and Alzheimer disease: For example, the association between APOE ε4 and HSV-1 in AD was first suggested by Ruth Itzhaki et al. in the late 1990s, when they reported that the odds of finding APOE ε4 allele in HSV-1 positive AD patients was almost 17 times higher compared to HSV-1 negative individuals without AD (OR 16.8, 95% CI: 3.61–77.8) [141].