The researchers identified mutations in the 10 suspect genes in 25 of the 51 children without family histories of cardiac hypertrophy and in 21 of the 33 with family histories.
"I think it's remarkable that we found mutations in nearly 50 percent of the kids who don't have family histories," Christine Seidman said.
The researchers also analyzed DNA from 11 pairs of parents and found that in seven of those couples, one parent had the same mutation as his or her child. The parents with these mutations believed their hearts were healthy, but echocardiograms revealed thickening of the muscle in some cases.
"We still don't know why the children presented symptoms so much earlier than their parents. We suspect that other genes must influence the disease presentation," Jonathan Seidman said.
Further genetic testing of children with cardiac hypertrophy and their parents may explain this and help doctors select appropriate treatments, the researchers said.
The study was published online April 9 in the New England Journal of Medicine.
The MedlinePlus Medical Encyclopedia has information about hypertrophic cardiomyopathy.
-- Robert Preidt
SOURCE: Harvard Medical School, news release, April 9, 2008
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