Porphyria cutanea tarda (PCT) is the most common porphyria worldwide. The underlying enzymatic deficiency in PCT is:
- A Porphobilinogen deaminase
- B Protoporphyrinogen oxidase
- C Uroporphyrinogen decarboxylase ✓
- D Ferrochelatase
Correct answer: C. Uroporphyrinogen decarboxylase
Explanation
PCT is caused by deficiency of uroporphyrinogen decarboxylase (UROD). The sporadic form involves inhibition of UROD in the liver by iron and oxidative stress. Porphobilinogen deaminase deficiency causes acute intermittent porphyria. Protoporphyrinogen oxidase deficiency causes variegate porphyria. Ferrochelatase deficiency causes erythropoietic protoporphyria.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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