Which of the following is not a porphyria?

• A. Acute intermittent porphyria
• B. Erythropoietic porphyria
• C. Porphyria cutanea tarda
• D. Sideroblastic anemia

Answer: (D)

Porphyrias are disorders caused by defects in the heme biosynthesis pathway, leading to the buildup of porphyrins or their precursors. This buildup can produce neurovisceral symptoms, skin photosensitivity, or both, depending on the specific type.

Acute intermittent porphyria is a classic neurovisceral porphyria that presents with episodes of abdominal pain, vomiting, and neurologic or psychiatric symptoms. Erythropoietic (congenital) porphyria is a rare form that often involves photosensitivity. Porphyria cutanea tarda is the most common cutaneous porphyria and presents with sun-exposed skin blistering and fragility.

Sideroblastic anemia, on the other hand, is a distinct disorder of heme synthesis within developing erythroid cells, characterized by microcytic anemia and ring sideroblasts in the bone marrow. It does not involve the porphyrin accumulation pattern or the characteristic neurovisceral or photosensitive features seen in porphyrias.

Therefore, sideroblastic anemia is not a porphyria.