WINSTON-SALEM, N.C. – Researchers at Wake Forest University School of Medicine reported a genetic link between diabetes, cardiovascular disease and metabolic syndrome (also called Syndrome X), at a recent meeting of the American Society of Human Genetics in Salt Lake City.
People with diabetes are at greatly increased risk of developing diseases of the blood vessels and resulting heart events. This new research indicates that the genetic tendency to have these conditions is inherited together.
“We reported evidence that type 2 diabetes, metabolic syndrome, and the tendency to have cardiovascular disease and resulting heart-related events are inherited together on specific parts of the human chromosomes,” said Donald W. Bowden, Ph.D., professor of biochemistry and internal medicine and associate director of the Wake Forest University Center for Human Genomics.
The findings are from the Diabetes Heart Study, a project to understand how genes and lifestyle influence the development of heart disease in diabetes families.
The study involved 1,180 people in 443 families from Forsyth County and the surrounding region. Each family includes at least two siblings who have diabetes. Researchers analyzed blood samples and DNA to locate regions of the human chromosomes that are connected with diabetes, metabolic syndrome, and cardiovascular disease.
“The results suggest that genes associated with the tendency for diabetes, cardiovascular disease and metabolic syndrome, are inherited as a single trait,” said Bowden. “The genes are at different locations on the chromosomes, which suggests that someone who has more than one of the genes may be more likely to have these diseases.”
Although specific genes have not yet been identified, two of the genes are found on chromosome 3 and the others are found on chromosomes 4 and 14.
“Our findings suggest that individual genes could be contributing to these important clinical conditions and that the conditions are being inherited together,” said Bowden. “This means these traits may be much more closely related than previously thought.”
Indeed, 463 of the 1,180 participants in the diabetes study reported they already had been told they had cardiovascular disease when the study began. “About half of the people with diabetes seem to have everything: diabetes, metabolic syndrome and cardiovascular disease,” said Bowden.
Diabetes is rapidly increasing in Americans and particularly among North Carolinians, where the frequency of diabetes may reach one in every 10 people by 2010.
“Cardiovascular disease,” as used in the study, refers to atherosclerosis, the buildup of fatty deposits and calcified plaque in the coronary and carotid arteries. Atherosclerosis can lead to heart attacks and strokes, although some people have heart attacks without evidence of atherosclerosis.
Metabolic syndrome, or Syndrome X, is characterized by high triglycerides, low HDL (good) cholesterol and high LDL (bad) cholesterol, elevated blood pressure, insulin resistance or glucose intolerance so the body can’t properly use insulin to process blood sugar, a greater tendency for blood to clot, and elevated levels of C-reactive protein in the blood, which is a measure of inflammation.
According to the American Heart Association, metabolic syndrome has become increasingly common in the United States, affecting more than 50 million Americans. It triples the risk of atherosclerotic heart disease and increases the risk for type 2 diabetes nearly five-fold.
Exactly how the individual genes are linked and inherited together is not clear and, Bowden said, is a subject for further study.
Bowden’s coauthors include Carl D. Langefeld, Ph.D., Stephen S. Rich, Ph.D., and Lynne Wagenknecht, Dr. P.H., from the Department of Public Health Sciences, Barry Freedman, M.D., from Nephrology, and J. Jeffrey Carr, M.D., from Diagnostic Radiology.
During the current fiscal year, Wake Forest researchers will receive more than $25 million to support research on diabetes. The funds are used for multiple projects ranging from basic studies targeted at understanding the causes of diabetes at the molecular level through clinical trials in which people with diabetes participate in studies aimed at reducing heart disease and other complications of diabetes by exercise programs or new drug therapies.
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Wake Forest University Baptist Medical Center is an academic health system comprised of North Carolina Baptist Hospital and Wake Forest University Health Sciences, which operates the university’s School of Medicine. U.S. News & World Report ranks Wake Forest University School of Medicine 30th in primary care, 41st in research and 14th in geriatrics training among the nation's medical schools. It ranks 32nd in research funding by the National Institutes of Health. Almost 150 members of the medical school faculty are listed in Best Doctors in America.