Thumb/wrist sign Positive when the thumb protrudes from the clenched fist, in which the other four digits are flexed over the thumb. Patient 1: This is a young man with Marfan’s syndrome. This patient also has a large wing span. Patient 2: This patient has Marfan’s syndrome. Share this: Click to share on Facebook (Opens in new window) Facebook Click to share on X (Opens in new window) X