XXYY syndrome discovered on routine physical examination

The XXYY syndrome, an uncommon disorder of chromosome number, was discovered on routine physical examination of a 20-year-old patient. Despite numerous earlier contacts with physicians, including several visits during adolescence, insufficient consideration had been given to his apparent abnormalities. This case is presented to review the syndrome and to emphasize the importance of careful evaluation of pubertal development during the routine physical examination of an adolescent.