A 40-year-old man of Afrikaner descent has lifelong blistering skin lesions on sun-exposed skin and now presents with acute abdominal pain and motor neuropathy after anticonvulsant use. Both faecal and plasma porphyrins are markedly elevated. The deficient enzyme is:

• A Protoporphyrinogen oxidase ✓
• B Coproporphyrinogen oxidase
• C Uroporphyrinogen decarboxylase
• D Porphobilinogen deaminase

Explanation

Variegate porphyria results from protoporphyrinogen oxidase deficiency and uniquely combines cutaneous photosensitivity with acute neurovisceral attacks. It is highly prevalent among South Africans of Afrikaner ancestry owing to a founder mutation. Coproporphyrinogen oxidase deficiency defines hereditary coproporphyria, uroporphyrinogen decarboxylase deficiency causes porphyria cutanea tarda without neurovisceral features, and porphobilinogen deaminase deficiency causes acute intermittent porphyria without photosensitivity.

Reference: Harrisons Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.