Dr. Srivastava and his colleagues of UT Southwestern Medical Center of Dallas discovered that the mutation in a gene NOTCH1 is responsible for aortic valve disease. Aortic valve disease is a common heart birth defect which causes adult heart disease.
The study was done in five generations of a Dallas family; the researchers studied the DNA mutations in all the 11 members of the family who were affected by aortic heart disease. The patients had severe calcium buildup on their heart valves and these valves were replaced. All the family members with the heart disease had mutations in the NOTCH1 gene.
Aortic valve disease occurs in 1% to 2% of world population. The normal aortic valve is made up of three leaflets or flaps of tissues that open and close to allow flow of blood through the valve in one direction. The aortic valve is located between the left ventricle, or lower chamber of the heart, and the largest artery, the aorta. The left ventricle pumps oxygen-rich blood into the aorta, which carries blood to the brain and the rest of the body. These patients with mutations has only two valve leaflets, this defect is called bicuspid aortic valve, and this condition is called as aortic valve stenosis, which causes narrowing of the passage for the blood flow.
"We know that aortic valve problems cause those deaths, so we think NOTCH1 mutations are likely the cause of some cases of hypoplastic left heart syndrome as well," said Dr. Srivastava. "Our work suggests that calcification of the aortic valve may be a manifestation of a mutation in NOTCH1 or related genes," Dr. Garg said. More studies his to be carried out to find the mechanism of NOTCH1 gene mutation to develop therapeutic agents for aortic valve disease. "Because of these families, we found that the NOTCH1 protein normally shuts down factors that control bone development, and this may provide clues for understanding why tissues become abnormally calcified in the setting of disease," Dr. Srivastava said.
A second, smaller family in San Diego afflicted with the heart disorder also had members with a second mutation in the same gene, providing convincing evidence that the researchers had found the genetic link to aortic heart disease, said Dr. Vidu Garg, assistant professor of pediatrics and molecular biology and lead author of the study.
Children's with aortic valve defects develop early calcification of their aortic valves which leads to severe heart disease in their adulthood. Aortic valve disease is the third most common cause of heart disease in adults. Due to severe calcification, the leaflets do not open normally which stops the proper supplying of blood to other parts of the body leading to replacement of the valves.