Erythropoietic Protoporphyria and X-linked Protoporphyria By Herbert L Bonkovsky, MD, Wake Forest University School of Medicine; Sean R Rudnick, MD, Wake Forest University School of Medicine Reviewed / Revised Dec 2022 View Patient Education Etiology Symptoms and Signs Diagnosis Treatment Key Points More Information Topic Resources Erythropoietic Protoporphyria... Erythropoietic Protoporphyria Erythropoietic Protoporphyria... Erythropoietic Protoporphyria... Doses of Beta-Carotene in... Erythropoietic protoporphyria (EPP) is due to an inherited deficiency in the activity of the enzyme ferrochelatase.