Table 2.

Cardinal clinical features of EPP/XLPP

• Presents as acute, non-disfiguring photosensitivity   Usual onset within first months of life   Infants become fussy, appear distressed, in pain after brief sun exposure   Acute redness, swelling of sun-exposed skin   Anecdotally referred to as “sun allergy”

• Diagnosis often delayed for years; sometimes made only in adults with major complications   Requires plasma + RBC porphyrin measurements   Many commercial labs report spuriously low values for these analytes   Urinary porphyrins are usually normal and not helpful for diagnosis

• Mild hypochromic, microcytic anemia is common in ~40% of patients   Iron-deficient phenotype (low serum ferritin, transferrin saturation) without iron loss

• Gall stones (due to PP) are common, even in those <40 years old

• PP hepatopathy with hepatic fibrosis or cirrhosis develops in 1%–3% of patients   Cholestasis may trigger or exacerbate   Causes include excess alcohol, drugs (body-building agents, estrogens), viral hepatitis, etc

Note: The diagnostic findings that are hallmarks of EPP/XLPP are delineated. Abbreviations: PP, protoporphyrin; EPP, erythropoietic protoporphyria; XLPP, X-linked protoporphyria; RBC, red blood cell.