Harvard Heart Letter

Harvard researchers identify genetic cause for a form of cardiomyopathy

Dilated cardiomyopathy is a disease of the heart muscle that affects its ability to pump. In people with this condition, the chambers of the heart become enlarged, and the walls become thin. Over time, the heart's ability to pump gradually weakens. Eventually, the heart becomes so weak that it is unable to pump a sufficient amount of blood to the body and lungs. This is heart failure.

Dilated cardiomyopathy can be caused by a variety of medical conditions and lifestyle choices, as well as genetic mutations. Recently, Dr. Jonathan Seidman and Dr. Christine Seidman, both professors of genetics at Harvard Medical School, discovered that a mutation on the TNN gene causes about 27% of inherited dilated cardiomyopathy cases and about 20% of cases that occur sporadically. Their research was published in the New England Journal of Medicine on February 16, 2012.

In their study of patients with dilated cardiomyopathy, hypertrophic cardiomyopathy, or healthy hearts, the Seidmans discovered a shortened TNN gene on more than a quarter of patients with the dilated form of the disease. No other cause for the disease could be identified. Analysis of their family members revealed that nearly 50% had parents or siblings with the same mutation, and 95% of these people had developed heart disease by age 40. Men were affected earlier and more seriously than women.

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