Arachnodactyly

**Definition:** An abnormal bone development that is characterized by extra long and slender hands and fingers, such that the clenched thumb extends beyond the ulnar side of the hand. Arachnodactyly can include feet and toes. Arachnodactyly has been associated with several gene mutations and syndromes.

**Tree numbers:** - C05.660.585.174 - C16.131.621.585.174