Patients with erythropoietic porphyria (Gunther's disease) have teeth that fluoresce with bright red color when subjected to ultraviolet radiation; their skin is light-sensitive, urine is red-colored. What enzyme can cause this disease, when it is deficient?

Answer options

1. Delta-aminolevulinate synthase
2. Ferrochelatase
3. Uroporphyrinogen III cosynthase
4. Uroporphyrinogen I synthase
5. Uroporphyrinogen decarboxylase

Explanation

(Gunther’s disease, GD) is a rare autosomal recessive disease. It results from the deficiency of uroporphyrinogen III synthase, the fourth enzyme on the metabolic pathway of heme synthesis.