Congenital Erythropoietic Porphyria
Angelika Erwin, Manisha Balwani, Robert J Desnick, Porphyrias Consortium of the NIH-Sponsored Rare Diseases Clinical Research Network, Margaret P Adam, Holly H Ardinger, Roberta A Pagon, Stephanie E Wallace, etc.
PMID: 24027798
Abstract:
Clinical characteristics:
Congenital erythropoietic porphyria (CEP) is characterized in most individuals by severe cutaneous photosensitivity with blistering and increased friability of the skin over light-exposed areas. Onset in most affected individuals occurs at birth or early infancy. The first manifestation is often pink to dark red discoloration of the urine. Hemolytic anemia is common and can range from mild to severe, with some affected individuals requiring chronic blood transfusions. Porphyrin deposition may lead to corneal ulcers and scarring, reddish-brown discoloration of the teeth (erythrodontia), and mild bone loss and/or expansion of the bone marrow. The phenotypic spectrum, however, is broad and ranges from non-immune hydrops fetalis in utero to late-onset disease with only mild cutaneous manifestations in adulthood.
Diagnosis/testing:
The diagnosis of CEP is supported by the biochemical findings of markedly decreased uroporphyrinogen (URO)-synthase activity in erythrocytes and/or markedly increased levels of urinary uroporphyrin I and coproporphyrin I isomers. The diagnosis is confirmed most commonly by identification of biallelic UROS pathogenic variants or on rare occasion by the identification of a hemizygous pathogenic variant in the X-linked gene GATA1.
Management:
Treatment of manifestations: There is no FDA-approved treatment for CEP or specific treatment for the photosensitivity. The only effective management is prevention of blistering by avoidance of sun and light exposure, including the long-wave ultraviolet light that passes through window glass or is emitted from artificial light sources. Therefore, the use of protective clothing, wraparound sunglasses, protective window films, reddish incandescent bulbs, filtering screens for fluorescent lights, and opaque sunscreens containing zinc oxide or titanium oxide is recommended. Wound care is necessary to prevent infection of opened blisters; surgical intervention may be necessary; blood transfusions are necessary when hemolysis is significant. Bone marrow transplantation (BMT) is the only cure for CEP and should be considered in children with severe cutaneous and hematologic involvement.
Prevention of primary manifestations: Strict avoidance of sunlight and other long-wave UV light exposure.
Prevention of secondary complications: Vitamin D supplementation, immunization for hepatitis A and B.
Surveillance: Monitor hematologic indices to assess hemolysis every six months. In those receiving transfusions: monitor for hemolysis more frequently and for iron overload. Monitor hepatic function and vitamin D 25-OH every six to twelve months in all patients.
Agents/circumstances to avoid: Avoidance of sunlight and UV light (see Treatment of manifestations). In those with hepatic dysfunction: avoid drugs that may induce cholestasis.
Evaluation of relatives at risk: Presymptomatic diagnosis is warranted in relatives at risk for initiation of early intervention (no phototherapy, strict sun protection) and future monitoring for signs of hemolytic anemia.
Pregnancy management: Protective filters for artificial lights should be used in the delivery/operating room to prevent phototoxic damage to the mother during delivery.
Other: Neither beta-carotene nor phototherapy with narrow-band ultraviolet B radiation has been beneficial.
Genetic counseling:
CEP caused by biallelic UROS pathogenic variants is inherited in an autosomal recessive (AR) manner. CEP caused by a GATA1 pathogenic variant is inherited in an X-linked (XL) manner.
Chemicals Related in the Paper:
