A 5-YEAR-OLD BOY, born in the United States to Pakistani parents, had a history of skin problems and the passage of pink-red urine since birth. He developed severe phototoxic reactions, including vesicles and bullae with resultant scarring, in areas of the skin exposed to the sun. His face was most severely affected (Figure 1). The dorsum of both hands demonstrated hyperpigmentation with irregular areas of hypopigmentation and skin atrophy (Figure 2). In addition to the cutaneous changes, on physical examination he was found to have hepatosplenomegaly and red-stained teeth.