ISTOCK, JXFZSYGenetic variants linked to a predisposition for Alzheimer’s disease and heavy smoking are less common in older people than in younger people, researchers report today (September 5) in PLOS Biology. Their study analyzed genetic alleles in two large genomic databases to find those associated with longevity, which they used as a proxy for evolutionary fitness.
“Nobody’s really had the data to measure single-generation shifts in allele frequencies in humans before,” says geneticist Jonathan Pritchard of Stanford University who was not involved in the study. “It’s an important part of understanding how evolution works to go down to the smallest scale of evolutionary change, namely, what’s happening in one generation.”
The idea for the study came about a few years ago, says senior author Joe Pickrell, after he used a commercial genomic testing service and put the resulting data online. One of his colleagues found that he carries a variant of the APOE4 gene that’s associated with an increased risk for Alzheimer’s disease. When Pickrell researched the variant, he found studies indicating that it’s less common in older people—and that carriers ...
