The progressive enlargement of the aorta (caused by the high blood pressure in this vessel) may cause its walls to become thin and weak. In rare cases, they may actually rupture, sometimes resulting in sudden death.

If the structure of the aortic or mitral valves is abnormal, there may be the leakage of blood at these points, resulting in fatigue, shortness of breath, and an irregular pulse.

People with Marfan's are often very tall and double-jointed, with proportionally long arms, legs, and fingers. They generally have weak connective tissues (such as tendons and ligaments) in various parts of the body, including the skeleton, eyes, heart, and other organs. Besides the difficulties in the heart already described, this may result in curvature of the spine and dislocation of the eye lenses. The severity of the symptoms of Marfan's Syndrome is variable.