Figure 5. Thumb and wrist sign frequently observed in patients with Marfan syndrome. The thumb sign is considered positive for Marfan syndrome if the hand is clenched and the thumb enclasped within is maximally opposed and protrudes beyond the ulnar border. The wrist sign is considered positive for the syndrome if there is overlapping of the distal phalanges of the first and fifth digits of one hand as they encircle the opposite wrist. These are subjective maneuvers that are helpful in determining the diagnosis. Arachnodactyly is a frequent feature of Marfan syndrome but may also be associated with other connective tissue disorders.