A 20-year-old woman complains of intermittent, colicky abdominal pain, fine tremors of her hands, excess sweating, and a general feeling of restlessness. Laboratory studies reveal an inherited defect in the biosynthesis of heme. This patient's genetic disease is most likely caused by deficiency of which of the following liver enzymes?

Acute intermittent porphyria is the most common genetic porphyria. This autosomal dominant genetic disease is caused by a deficiency of porphobilinogen deaminase activity in the liver. Clinical symptoms include colicky abdominal pain and neuropsychiatric symptoms. Choices A, B, and D are not involved in heme biosynthesis. Deficiency of uroporphyrinogen decarboxylase (choice E) causes a chronic hepatic porphyria that typically presents with cutaneous photosensitivity and iron overload in the middle-aged or elderlyDiagnosis: Porphyria, acute intermittent