Supravalvular aortic stenosis (SVAS) is a type of heart defect that develops before birth. It is characterized by a narrowing (stenosis) of the section of the aorta just above the valve that connects the aorta to the heart (aortic valve). The severity of SVAS varies from person to person; some individuals may die in infancy while others never experience symptoms. If symptoms develop, they may include shortness of breath, chest pain, murmur, and/or eventual heart failure. Some affected individuals also have defects in other blood vessels, such as the pulmonary artery. SVAS can be caused by mutations in the ELN gene and be inherited in an autosomal dominant manner, although some individuals that inherit the mutated gene never develop features of the condition (called reduced penetrance). SVAS can also be associated with Williams syndrome. Treatment may include surgery to repair the condition in severe cases.