HOUSTON--(March 16, 2002)--The failure of dystrophin, one of the building blocks that literally holds heart muscle cells together, can cause dilated cardiomyopathy (DCM), a condition in which the pumping chambers of the heart enlarge and cannot pump adequately, according to researchers at Baylor College of Medicine in a report in todays issue of the journal The Lancet.
However, allowing the heart to rest by using a mechanical device called a ventricular assist device or VAD allows dystrophin to resume its function and restores the heart to more normal pumping, said Dr. Jeffrey Towbin, professor of pediatrics and cardiology at Baylor and the senior author of the report.
Dystrophin is probably best known for its relationship to Duchenne and Becker muscular dystrophy, diseases in which the muscles weaken, the child requires a wheelchair and dilated cardiomyopathy occurs. A mutation in the dystrophin gene causes these diseases.
However, in the case of dilated cardiomyopathy alone, the end portion of the dystrophin protein loses a critical connection between the cells contractile apparatus and the cellular membrane. As a result, the heart cannot contract adequately, said Drs. Jeffrey Towbin and Neil Bowles, also a member of the Baylor research team.
Towbin and his colleagues took samples from 10 patients with ischemic (disease of the coronary artery) and 10 patients with non-ischemic dilated cardiomyopathies resulting from different causes who were awaiting heart transplants. Samples were also obtained from six patients with dilated cardiomyopathy who were being treated with these ventricular assist pumps. They compared the patient samples to normal samples taken from transplanted hearts and found the abnormality in the dystrophin of roughly 90 percent of all the patients with cardiomyopathy.
There are two theories about why the protein becomes disconnected. One is mechanical. As the heart pumps harder and harder over a number o
Contact: Lori Williams/Ron Gilmore
Baylor College of Medicine