As a group, Asian Indians have one of the highest rates of heart disease in the world, three times higher than in the United States. In spite of a fairly healthy lifestyle, many Asian Indians have very high levels of the blood fat triglyceride and low levels of HDL (the good cholesterol), as well as a high incidence of diabetes. Researchers have been trying to figure out why the group is at higher risk.
Now, a University of Maryland Medical Center study provides evidence that a genetic abnormality could explain the difference. The study results were presented on November 8 at the 72nd Annual Scientific Sessions of the American Heart Association in Atlanta, Georgia.
"We found that a genetic abnormality in triglyceride regulation appears to be common among Asian Indians," says Michael Miller, M.D., director, Center for Preventive Cardiology at the University of Maryland Medical Center and principle investigator of the study. "We think this abnormality prevents blood fats from being broken down effectively and, as a result, triglyceride levels may accumulate to dangerously high levels," says Dr. Miller, who is also an associate professor of Medicine at the University of Maryland School of Medicine.
For the study, Dr. Miller analyzed blood samples and DNA from 100 people of Asian Indian decent who had gathered at an Indian festival in Northern Virginia and volunteered to have their blood drawn. The vast majority of the people tested, 70 percent, had the same genetic abnormality in triglyceride regulation, placing them at increased risk of heart disease.
Triglyceride is a type of fat that is always circulating in the blood, especially after a meal high in saturated fat. Usually, triglyceride particles are broken down by enzymes. When that process is not working efficiently, the triglycerides that are only partially broken down can cause fatty deposits in blood vessels, leading to atherosclerosis, known as hardening of the arteries.
Triglycerides have also been shown to increase the risk of blood clots, which combine with fatty deposits in the coronary vessels to cause heart attacks. Previous work by Dr. Miller and his research team demonstrated that triglyceride levels above 100 mg/dL increase the risk of heart disease. The average triglyceride level among the Asian Indians in this study who had the genetic abnormality was approximately 350 mg/dL. In addition, 33 percent had a family history of heart disease and 20 percent had diabetes.
Studies have shown that the genetic abnormality found to be prevalent in this Asian Indian population is also involved with insulin regulation. That might explain the high rates of diabetes observed in this population.
Other members of Dr. Miller's team include Jeffrey Rhyne, M.S, and Meena Khatta, R.N., at the University of Maryland Medical Center, Karen Zeller, M.S. at The Johns Hopkins Hospital and Hemal Parekh, M.D. at Stanford University Medical Center.