Gene Influences Heart Disease And Stroke Risk Factors

February 11, 1999

DALLAS, Feb. 11 -- Researchers may have pieced together part of the puzzle about why some individuals with many risk factors for atherosclerosis never develop heart disease and stroke while others with few risk factors do.

Their findings are reported this month's Arteriosclerosis, Thrombosis and Vascular Biology: Journal of the American Heart Association.

According to the study's lead author, Sharon L.R. Kardia, M.D., and colleagues at the University of Michigan, Ann Arbor, the gene responsible for regulating levels of certain fats in the bloodstream also appears to determine how much influence cholesterol and other risk factors have on atherosclerosis, the disease process that leads to heart attacks and strokes.

The gene that Kardia and her colleagues say affects the influence of risk factors is apolipoprotein E (Apo E). Apo E is a protein on the "good" cholesterol and "bad" cholesterol in the blood which helps deliver the cholesterol to the liver and elsewhere in the body.

"Whether a risk is really a risk factor for a particular individual may be determined in part by the form of their Apo E gene," she says. The findings are in line with the current understanding of the complexity of heart disease and stroke because not everyone with many risk factors develops cardiovascular disease.

Kardia, assistant professor of epidemiology, examined the relationship between risk factors, atherosclerosis, and the genetic makeup of 169 women and 160 men who were participants in the Rochester Family Heart Study.

Atherosclerosis is a disease in which calcium, along with fats and cholesterol, collect in the blood vessel to form plaques. The plaques can block blood flow to the heart or brain, triggering a heart attack or stroke. Participants had no prior signs of heart disease and had not suffered a stroke. All participants were under 60 years of age.

To detect early signs of atherosclerosis, researchers used electron-beam-computed tomography. This technique can detect calcium in plaques in individuals without symptoms of heart disease and stroke.

Different versions of the Apo E gene exist. They are E-2, E-3 and E-4. These combine to form six possible Apo E genotypes (3/2, 3/3, 4/3, etc.). E-3/3 is the most common genotype in the general population.

Kardia and her colleagues sought to determine the influence of specific Apo E genotypes in predicting the risk of developing early calcification of the arteries in the individuals studied. They were looking to determine which specific risk factors were associated with the development of early calcification.

The Apo E-4/3 genotype in women was associated with calcification if the women had an increased body mass index and increased blood levels of triglycerides. But, in contrast, the E-3/3 genotype was not associated with calcification in these risk groups. Body mass index (BMI) is a measure used to classify people on the basis of body density, which reflects fat levels. A BMI higher than 30 is considered obese. Obesity is a risk factor for heart disease. In men the E-4/3 genotype was associated with calcification if the men had increased body mass index, but not elevated cholesterol levels. In contrast those with the E-3/3 genotype had a lower risk.

"Although we do not have the knowledge of the biological mechanisms to explain why some genotypes are more at risk than others, we do know that disease susceptibility in individuals is a consequence of interactions between genetic and environmental factors," she says. "These kinds of studies might help explain some of that variation and have implications for treatment." According to Kardia, individuals with one type of Apo E may need to focus primarily on controlling their blood levels of cholesterol rather than other risk factors.

"However, before we can use this kind of information the way we use a cholesterol test, we need to have a large prospective study in which healthy individuals are followed over time to confirm these associations that we have found in our study on how the Apo E gene affects risk of heart disease and stroke," says Kardia.

Co-authors are M.B. Haviland, M.D.; C.F. Sing, M.D., University of Michigan, Ann Arbor; and R.E. Ferrell, University of Pittsburgh.
Media advisory: Dr. Kardia can be reached at 734-936-0866. (Please do not publish numbers)

American Heart Association

Related Heart Disease Articles from Brightsurf:

Cellular pathway of genetic heart disease similar to neurodegenerative disease
Research on a genetic heart disease has uncovered a new and unexpected mechanism for heart failure.

Mechanism linking gum disease to heart disease, other inflammatory conditions discovered
The link between periodontal (gum) disease and other inflammatory conditions such as heart disease and diabetes has long been established, but the mechanism behind that association has, until now, remained a mystery.

New 'atlas' of human heart cells first step toward precision treatments for heart disease
Scientists have for the first time documented all of the different cell types and genes expressed in the healthy human heart, in research published in the journal Nature.

With a heavy heart: How men and women develop heart disease differently
A new study by researchers from McGill University has uncovered that minerals causing aortic heart valve blockage in men and women are different, a discovery that could change how heart disease is diagnosed and treated.

Heart-healthy diets are naturally low in dietary cholesterol and can help to reduce the risk of heart disease and stroke
Eating a heart-healthy dietary pattern rich in vegetables, fruits, whole grains, low-fat dairy products, poultry, fish, legumes, vegetable oils and nuts, which is also limits salt, red and processed meats, refined-carbohydrates and added sugars, is relatively low in dietary cholesterol and supports healthy levels of artery-clogging LDL cholesterol.

Pacemakers can improve heart function in patients with chemotherapy-induced heart disease
Research has shown that treating chemotherapy-induced cardiomyopathy with commercially available cardiac resynchronization therapy (CRT) delivered through a surgically implanted defibrillator or pacemaker can significantly improve patient outcomes.

Arsenic in drinking water may change heart structure raising risk of heart disease
Drinking water that is contaminated with arsenic may lead to thickening of the heart's main pumping chamber in young adults, according to a new study by researchers at Columbia University Mailman School of Public Health.

New health calculator can help predict heart disease risk, estimate heart age
A new online health calculator can help people determine their risk of heart disease, as well as their heart age, accounting for sociodemographic factors such as ethnicity, sense of belonging and education, as well as health status and lifestyle behaviors.

Wide variation in rate of death between VA hospitals for patients with heart disease, heart failure
Death rates for veterans with ischemic heart disease and chronic heart failure varied widely across the Veterans Affairs (VA) health care system from 2010 to 2014, which could suggest differences in the quality of cardiovascular health care provided by VA medical centers.

Heart failure: The Alzheimer's disease of the heart?
Similar to how protein clumps build up in the brain in people with some neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, protein clumps appear to accumulate in the diseased hearts of mice and people with heart failure, according to a team led by Johns Hopkins University researchers.

Read More: Heart Disease News and Heart Disease Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to