APOE ε2 protective effect may not be universal across ancestries, preprint finds
Analysis of admixed Brazilian elderly cohorts finds deviations from expected APOE ε2 genotype frequencies, raising questions about whether its longevity-protective role generalises beyond European-ancestry populations.
The APOE gene is one of the best-characterised genetic determinants of Alzheimer's disease risk and longevity. The ε2 allele has long been regarded as protective — reducing Alzheimer's disease risk and associated with longer lifespan — but that understanding is grounded almost entirely in cohorts of European ancestry.
A preprint posted to bioRxiv reports findings from two Brazilian elderly cohorts with high levels of admixture across African, Indigenous American, and European ancestral backgrounds. Using local ancestry resolution — a technique that identifies the ancestral source of each chromosomal segment individually — the authors find statistically significant deviations from Hardy-Weinberg equilibrium at the APOE locus, particularly in individuals carrying ε2 on non-European genomic backgrounds. The observed genotype frequencies suggest that the survival advantage conferred by ε2 may differ substantially depending on local genomic context.
The study does not overturn the established literature on APOE ε2, but it adds to a growing body of work highlighting that variant-effect estimates from predominantly European datasets may not transfer cleanly to admixed or non-European populations. The authors argue that local ancestry modulates APOE's impact on survival, and that population-specific analyses are necessary to characterise the allele's role in diverse groups.
The work is a preprint and has not yet been peer-reviewed. Replication in independent admixed cohorts and further functional characterisation will be needed before firm conclusions can be drawn.
Plain-language version
For patients, families, and general readers. Educational only — not medical advice.
The APOE gene influences the risk of Alzheimer's disease and how long people live. One version of this gene, called APOE ε2 (epsilon 2), has long been thought to be protective — meaning it is linked to a lower risk of Alzheimer's and a longer life. Most of what scientists know about this comes from studies of people with European ancestry.
Researchers in Brazil have now looked at elderly people whose ancestry is a mixture of African, Indigenous American, and European backgrounds — a common pattern in Brazil. Their analysis, which has not yet been formally reviewed by other scientists, suggests that the protective effect of APOE ε2 may not work in exactly the same way in people with this kind of mixed ancestry. The team found unexpected patterns in how often the ε2 version appeared in these populations.
This does not mean the gene suddenly works differently for any individual; it highlights that more research is needed in diverse populations to understand how genetic variants behave across different ancestral backgrounds. This is an educational summary, not medical advice. If anything here raises questions for you, please speak with your GP or a clinical professional.
Sources
Read the original reporting — these are the public sources this summary draws from.
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Primary sourcePreprint bioRxiv (Cold Spring Harbor Laboratory) · 2026-06-23Is APOE ε2 always a protective allele? Deviations in Hardy-Weinberg equilibrium in admixed Brazilian elderly individuals