A 5-year-old boy presents with severe blistering skin lesions on sun-exposed areas, pink urine, and haemolytic anaemia. Enzyme assay shows uroporphyrinogen III synthase deficiency. What is the inheritance pattern?

• A Mitochondrial
• B Autosomal dominant
• C X-linked recessive
• D Autosomal recessive ✓

Explanation

Congenital erythropoietic porphyria (Gunther disease) is autosomal recessive. Both alleles of the UROS gene must be defective. This contrasts with AIP, PCT, HCP, and VP, which are autosomal dominant. X-linked protoporphyria involves ALAS2 gain-of-function, not uroporphyrinogen III synthase.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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