Common Alzheimer ’s disease gene may have helped our ancestors have more kids

Roughly one in five people are born with at least one copy of a gene variant called APOE4 that makes them more prone to heart disease and Alzheimer’s disease in old age. That the variant is so common poses an evolutionary mystery: If it decreases our fitness, why hasn’t APOE4 been purged from the human population over time? Now, a study of nearly 800 women in a traditional society in the Amazon finds that those with the disease-promoting variant had slightly more children. Such a fertility benefit may have allowed the gene to persist during human evolution despite its harmful effects for older people today. “The study results are fascinating and illustrate that people living in rural, nonindustrial, and nonmechanized environments can provide perspective on the biology and health of those of us in industrialized areas of the world,” says biological anthropologist Cynthia Beall of Case Western Reserve University, who was not involved with the research. The APOE gene encodes apolipoprotein E, a molecule that helps the body transport cholesterol in the blood. There are three main variants and people can inherit a mix from their parents, with the one called APOE3 being much more common than APOE4 . In populations of European ancestry, having one copy of APOE4 raises a person’s risk of cardiovascular disease and triples their odds of developing Alzheimer’s disease; those with two copies face a...
Source: Science of Aging Knowledge Environment - Category: Geriatrics Source Type: research