Research Review Specifies Genetic Basis of Enlarged Heart

FOR RELEASE: 4 p.m. EDT, MondayOctober 22, 2001

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American Heart Association journal report:Research review specifies genetic basis of enlarged heart

DALLAS, Oct. 23 -- Enlargement of the heart muscle is the most common cause of sudden cardiac death in the young, and it is now estimated to affect one in every 500 adults. Alarmingly, all too often its first symptom is death.

In today's issue of Circulation: Journal of the American Heart Association, a pair of researchers review the most recent research into the genetic roots of this single-gene disorder.

Hypertrophic cardiomyopathy (HCM) is enlargement of the heart muscle without an increase in the size of the heart's chambers.

Ten genes have been identified in relation to HCM. Each encodes for a protein that helps the heart muscle beat. Mutations cause a lack of muscle contractility as well as a buildup of interstitial fibrosis, which is scar tissue that cannot contract. While two mutations are thought to be responsible for 70 to 80 percent of all cases of hereditary or familial HCM, more than 100 mutations have now been identified, with more still being found.

The good news: "Results to date suggest certain mutations have significant prognostic value in predicting sudden cardiac death," says author Robert Roberts, M.D., of the Section of Cardiology at Baylor College of Medicine in Houston.

The incidence of sudden cardiac death is greater in people with familial HCM who engage in competitive contact sports. It is also greater in males with familial HCM. The disease appears in adolescence and young adulthood and is seldom detected before puberty by clinical exam, electrocardiogram or echocardiogram. Therefore, genetic identification could provide the chance to detect the disease a full decade before onset.

"Identification of the genes is the first necessary step in preparation for genetic screening of these families and athletes with family histories of HCM," says Roberts, who is president-elect of the American Heart Association. "We are very hopeful that technology in the near future will be make it possible to have routine, rapid genetic screening for these mutations."

Roberts' co-author is Ulrich Sigwart, M.D., of the Royal Brompton Hospital in London. The review was funded in part by the National Institutes of Health.

###NR01-1371 (Circ/Roberts)

Media Advisory: Dr. Roberts can be reached at (713) 790-4864 (Please do not publish contact information.)