Evidence check: APOE in the context of longevity

APOE is the most well-studied genetic risk factor for late-onset Alzheimer's disease. The ε4 allele (rs429358, rs7412) significantly increases Alzheimer risk, but does not guarantee reduced lifespan—many ε4 carriers live into old age. The ε2 allele appears mildly protective. However, the association is population-dependent (e.g., weaker in African ancestries). A DNA test alone cannot predict longevity, as lifestyle, diet, exercise, education, and social factors dominate. Consumer tests like MyBody-X may report APOE, but results are probabilistic, not diagnostic. An ε4 result can cause unnecessary anxiety without actionable certainty. Evidence: human-strong for Alzheimer, human-moderate for longevity. Caveat: do not self-diagnose; consult a physician for interpretation.