How I treat erythropoietic protoporphyria and X-linked protoporphyria

Abstract

Erythropoietic protoporphyria (EPP) is an inherited cutaneous porphyria caused by reduced expression of ferrochelatase, the enzyme that catalyzes the final step in heme biosynthesis. The resultant accumulation of protoporphyrin IX leads to severe painful cutaneous photosensitivity, as well as potentially life-threatening liver disease in a small percentage of patients. X-linked protoporphyria (XLP) is similar to EPP clinically, but results from increased activity of δ-aminolevulinic acid synthase 2 (ALAS2), the first step in heme biosynthesis in the bone marrow, and also causes protoporphyrin accumulation. Although historically the management of EPP and XLP (collectively termed protoporphyria) centered around avoidance of sunlight, novel therapies have recently been approved or are in development, which will alter the therapeutic landscape for these conditions. We present three patient vignettes highlighting key treatment considerations in patients with protoporphyria including (1) approach to photosensitivity, (2) managing iron deficiency in protoporphyria, and (3) understanding hepatic failure in protoporphyria.