WEDNESDAY, Feb. 15 (HealthDay News) -- Researchers have discovered a defective gene that's responsible for more than one-quarter of cases of inherited dilated cardiomyopathy, a serious heart muscle disease that often leads to heart failure by middle age.
In the study, published in the Feb. 16 issue of the New England Journal of Medicine, researchers analyzed the DNA of 312 people with dilated cardiomyopathy, 231 people with another form of heart muscle disease (called hypertrophic cardiomyopathy) and 249 people with healthy hearts.
The study patients with dilated cardiomyopathy had no obvious cause for their disease -- such as alcoholism, heart attacks and other infections -- so the researchers believed there was a genetic origin for the disease in these patients.
About 27 percent of the dilated cardiomyopathy patients had mutations on the TTN gene that shortened the length of the gene.
Only 1 percent of the patients with the other form of cardiomyopathy and 3 percent of patients with healthy hearts had similar mutations, the investigators found.
Further analysis of family members' DNA revealed that up to half of the dilated cardiomyopathy patients had first-degree relatives (including parents and siblings) who also had the TTN mutation by age 40, and of those, nearly all (95 percent) had some sign of heart disease, said study co-leader Jonathan Seidman, a professor of genetics at Harvard Medical School.
Seidman's wife, Dr. Christine Seidman, a professor of genetics and a cardiologist at Harvard, was the other study co-leader.
The researchers also estimate that about 20 percent of sporadic cases of the disease, that is, dilated cardiomyopathy that isn't passed down from parents, involve a TTN mutation.
In dilated cardiomyopathy, the chambers of the heart become enlarged, the walls thin and the ability of the heart to pump is impaired. W
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