Marfan's syndrome. Hands of a young woman with Marfan's syndrome, showing double-jointedness and long fingers. The patient is able to curl her long fingers around her wrist while stretching the index finger to show its spidery" thinness. These thin "spidery" fingers are also known as arachno- dactyly. Marfan's syndrome is a rare genetic disorder of connective tissue. Affected people grow very tall and thin, with long fingers. The chest and spine are often deformed, and joints are weak and prone to dislocation. Other symptoms include heart abnormalities and eye lens disloca- tion. Heart failure is common before age 50."