Cambridge, Mass. Wed. June 18, 2014 – By scouring the DNA of thousands of patients, researchers at the Broad Institute, Massachusetts General Hospital, and their colleagues have discovered four rare gene mutations that not only lower the levels of triglycerides, a type of fat in the blood, but also significantly reduce a person's risk of coronary heart disease — dropping it by 40 percent. The mutations all cripple the same gene, called APOC3, suggesting a powerful strategy in developing new drugs against heart disease. The work, which appears in the June 18 issue of the New England Journal of Medicine, sheds light on the biological role of triglycerides and contributes to a growing body of knowledge that suggests that high triglyceride levels — rather than low HDL, another type of fat in the blood — are a major culprit in heart disease.
What I find intriguing about this story: crippling a gene probably extends life, at least for humans living in modern industrial environments.
"Genetic load" mutations are mutations that just plain make us worse off. We all have such mutations, perhaps hundreds or thousands of harmful mutations in each of us. I wonder how often mutations start out as genetic load mutations (harmful under the circumstances) but become beneficial when circumstances change.
Did mutations that messed up the function of APOC3 exist in small numbers of individuals hundreds and thousand of years ago? Probably. Were they harmful to humans on average back then? Quite possibly. We might have many mutations scattered around the human population in low frequencies today that would be good to have more widely distributed because conditions have changed to make those mutations more beneficial.
Given our diets and lower levels of exercise today it seems reasonable to expect we will find people who have mutations that were neutral or harmful to their ancestors but which are beneficial to people who have them in current conditions. Some mutations around diet that, say, reduce appetite or that reduce the body's response to a high sugar diet might be beneficial where even as recently as the 19th century they were harmful.
|Share |||Randall Parker, 2014 August 16 09:22 PM|