Variants thought to be behind inherited conditions prove difficult to pin down
SAN FRANCISCO — Rare tweaks in single letters of DNA are not as powerful a force in health and in common diseases as scientists hoped, new work suggests.
Common genetic variants contribute only a tiny bit to a person’s risk of developing particular diseases, so researchers have turned to rare variants as a possible explanation for why some people inherit a propensity for heart disease, diabetes or other common ailments. These rare variants, present in a small percentage of people, are thought to affect how genes work. Two separate attempts to link rare variants with disease suggest that they may not affect disease risk more than common variants do.
“We have learned that the effect size of these very rare variants is quite small,” statistical geneticist Suzanne Leal of Baylor College of Medicine in Houston said November 6 during the annual meeting of the American Society of Human Genetics.