A patient presents with severe abdominal pain, neuropsychiatric symptoms, and port-wine-colored urine after starting phenobarbital. This constellation of symptoms is characteristic of acute intermittent porphyria (AIP), which results from a deficiency in which enzyme?
✓ Correct Answer: Option C
AIP is caused by hydroxymethylbilane synthase deficiency, leading to accumulation of porphyrin precursors. Phenobarbital induces cytochrome P450, increasing heme synthesis demand and worsening symptoms.