This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: HAEM synth and porphyrias, Subject name: Biochemistry
Most common porphyria in humans is due to deficiency of which of the following enzyme: 
Select and explain. 
A. PBG deaminase, B. Uroporphyrinogen decarboxylase, C. Ferrochelatase, D. Coproporphyrinogen oxidase
B: Uroporphyrinogen decarboxylase
Answer: B: Uroporphyrinogen decarboxylase 
Explanation: Porphyria Cutanea Tarda is the most common porphyria. Enzyme defect:- Uroporphyrinogen decarboxylase Sporadic (type 1) Familial (type 2) Can also develop after exposure to halogenated aromatic hydrocarbons. MC Acute porphyria - Acute intermittent porphyria MC porphyria in children - Erythropoietic protoporphyria