Acute intermittent porphyria with transient cortical blindness.

Acute intermittent porphyria is a hereditary disorder characterized by deficient activity of the enzyme porphobilinogen deaminase. It manifests with occasional neurovisceral crises due to overproduction of porphyrin precursors. We report a 12 year old male child with acute intermittent porphyria, who presented with encephalopathy and transient blindness of cerebral origin.