Up to 15% of adults with Turner syndrome have bicuspid aortic valves, meaning only two, instead of three, parts to the valves in the main blood vessel leading from the heart are present. Since bicuspid valves are capable of regulating blood flow properly, this condition may go undetected without regular screening. However, bicuspid valves are more likely to deteriorate and later fail. Calcification also occurs in the valves, which may lead to a progressive valvular dysfunction as evidenced by aortic stenosis or regurgitation.