Supravalvular aortic stenosis (SVAS) is an uncommon vascular defect causing blood flow obstruction that usually develops in the first few years of life.
This defect is a narrowing (stenosis) of the large blood vessel that carries blood from the heart to the rest of the body (the aorta), especially at major branch points.
The condition is described as supravalvular because the section of the aorta that is narrowed is located just above the valve that connects the aorta with the heart (the aortic valve).
Isolated SVAS is caused by genetic changes in the elastin gene (ELN) that can be passed from parent to child. Elastin defects are associated with connective tissue abnormalities, such joint problems, hernias, and cardiovascular disease. In children with Williams syndrome, the elastin gene is deleted along with 25-27 other genes that cause developmental delays and hormone problems.
The elastin gene provides instructions for making a protein called tropoelastin. Elastin is the major component of elastic fibers, which are slender bundles of proteins that provide strength and flexibility to the connective tissue that supports the body's organs and tissues such as the heart, blood vessels, skin, lungs and ligaments.