Genes Linked to Cardiac Risk

Researchers have discovered seven new genes that affect cholesterol levels in humans and that may influence the risk of heart disease.

The research, conducted by scientists at Harvard, the University of Michigan, and the University of North Carolina, may be used in the future to help develop specifically targeted cholesterol medications.

“We could potentially figure out the most appropriate medication for each person, because it might not be the same for everyone,” said senior author of the study and professor at the University of Michigan, Goncalo R. Abecasis. He said there is potential to use the genes to build a specific genetic lipid profile for each person.

The study, published this week in Nature Genetics, also verified the role of 11 previously discovered genes that work to modify cholesterol levels.

The researchers identified 18 regions of the genome that account for about 25 percent of the variance in blood cholesterol levels, according to Abecasis.

Because most illnesses aren’t caused by a single gene, research today often focuses on discovering the genes that, when aggregated in an individual, contribute to disease, according to Mason W. Freeman ’73, professor at Harvard Medical School and chief of the Lipid Metabolism Unit at Massachusetts General Hospital.

“This begins to explain why people can have the same diet and exercise patterns and have different cholesterol numbers,” he said.

Increased levels of cholesterol, a lipid found in cell membranes, have been shown to promote hardening of the arteries, which can lead to cardiovascular disease.

There are two main types of cholesterol: LDL, the “bad” cholesterol, and HDL, the “good” cholesterol.

LDL has been shown to increase the risk of heart attacks and strokes, and is the type of cholesterol that has been successfully treated with pharmaceuticals. HDL has long been considered a protective factor, lowering the chances of heart disease.

The study found that only the genetic changes that are associated with LDL cholesterol influence the risk of heart disease.

“We know that LDL is causal to the buildup of fatty plaques in the heart arteries, but it now looks like simple blood measurements of HDL may not be causal,” said study author Sekar Kathiresan, an instructor in medicine at the Medical School and director of preventive cardiology at Massachusetts General Hospital Instead, the proposed protective qualities of high HDL may vary for each person.

For recent research, faculty profiles, and a look at the issues facing Harvard scientists, check out The Crimson's science page.