March 27, 2009

Grim News About Childhood Heart Disease

Scientists have discovered grim news about a recently recognized and rare type of genetic heart disorder -- it progresses rapidly and often results in early death, according to a new study.

Mutations in the lysosome-associated membrane protein gene (called LAMP2) produce cardiomyopathy, or a disorder of the heart muscle, in young patients that is similar to severe hypertrophic cardiomyopathy, a condition in which the heart muscle becomes thick, making it harder for blood to leave the heart and forcing the heart to work harder to pump blood.

This disorder, which is also called Danon disease, usually affects young boys. Researchers said their study found that clinical deterioration is often rapid, with the time interval from clinical stability with little or no symptoms to end-stage heart failure as brief as six months.

In their study, diagnosis was the result of a heart murmur, family screening and findings on routine electrocardiogram (ECG) or by symptoms such as chest pain or fainting. The seven children involved in the study were between 7 and 17 years old at the time of diagnosis, and during the subsequent average time of 8.6 years after diagnosis, each of the patients experienced serious adverse clinical consequences by 14 to 24 years of age. Four of the patients died and one underwent a heart transplant.

The researchers called Danon disease "one of the most lethal cardiomyopathies in young and usually male patients."

"The early experience with the distinctive natural history and prognosis of patients with LAMP2 mutations establishes the importance of molecular diagnosis and underscores the utility of genetic testing," the authors said.

SOURCE: Journal of the American Medical Association, 2009;301:1253-1259