Chapter 124: Erythropoietic Protoporphyria

ERYTHROPOIETIC PROTOPORPHYRIA

Therapeutic Approach

Erythropoietic protoporphyria (EPP) is the third most common porphyria and the most common in children. EPP results from loss of function mutation of ferrochelatase (FECH), the last enzyme of the heme biosynthetic pathway. Gain of function mutation of ALAS2, the erythroid-specific form of the first enzyme in the pathway, causes X-linked protoporphyria (XLP) which has the same phenotype as EPP. Both are characterized by an acute, painful, and nonblistering type of cutaneous photosensitivity and rarely protoporphyric hepatopathy, which may require liver transplantation. Photoprotection, especially avoidance of sunlight exposure, is the primary therapeutic intervention. Afamelanotide, a synthetic analogue of α-melanocyte-stimulating hormone, increases skin melanin and improves sunlight tolerance. See Table 124-1.

Levels of evidence are based on the Journal of the American Academy of Dermatology guidelines: level IA evidence includes evidence from meta-analysis of randomized controlled trials; level IB evidence includes evidence from ≥1 randomized controlled trial; level IIA evidence includes evidence from ≥1 controlled study without randomization; level IIB evidence includes evidence from ≥1 other type of experimental study; level III evidence includes evidence from nonexperimental descriptive studies, such as comparative studies, correlation studies, and case control studies; and level IV evidence includes evidence from expert committee reports or opinions or clinical experience of respected authorities, or both.

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