Marfan syndrome is a multi-systemic genetic disorder that affects the connective tissue. Those with the condition tend to be tall and thin, with long arms, legs, fingers, and toes. They also typically have exceptionally flexible joints and abnormally curved spines. The most serious complications involve the heart and aorta, with an increased risk of mitral valve prolapse and aortic aneurysm. However, the severity of the symptoms is variable. Both Abraham Lincoln and Julius Caesar are speculated to have suffered from this disorder, both due to family history and historical evidence.

Source: Wikipedia