New insights into the pathogenesis of erythropoietic protoporphyria and their impact on patient care.

Abstract

UNLABELLED:

Erythropoietic protoporphyria (EPP, MIM 177000) is an inherited disorder caused by a partial deficiency of ferrochelatase (FECH) which catalyses the chelation of iron into protoporphyrin to form haem. The majority of EPP patients experience solely a painful photosensitivity whereas a small number of them develop liver complications due to the accumulation of excessive amount of protoporphyrin in the liver. EPP is considered to be an autosomal dominant disorder, however, with a low clinical penetrance. To date, a total of 65 different mutations have been identified in the FECH gene of EPP patients. Among the 89 EPP patients who carry a "null allele" mutation which results in the formation of a truncated protein, 18 of them developed EPP-related liver complications. None of the 16 missense mutations identified among 19 patients on the other hand, have been associated with liver disease (P = 0.038). The allelic constellation of an overt patient consists of a mutated FECH allele and a "low expressed" normal allele and that of an asymptomatic carrier, a combination of a mutated and a normally expressed FECH allele. The identification of the "low expressed" allele is facilitated by haplotype analysis using two single nucleotide polymorphisms, -251 A/G in the promoter region and IVS1-23C/T. At the current time when only partially effective therapies are available, the disclosures of both "null allele" and the "low expression" mechanisms will improve patient management.

CONCLUSION:

While covering the important clinical aspect of erythropoietic protoporphyria, this article emphasises the latest achievements in the molecular genetics of the disorder.

• Authors: X Schneider-Yin, L Gouya, A Meier-Weinand, J C Deybach, E I Minder
• Journal: European journal of pediatrics (Eur J Pediatr) Vol. 159 Issue 10 Pg. 719-25 (Oct 2000) ISSN: 0340-6199 [Print] Germany
• PMID: 11039124 (Publication Type: Journal Article, Review)

Chemical References

• Ferrochelatase

Topics

• Alleles
• Ferrochelatase (metabolism)
• Genetic Predisposition to Disease
• Heterozygote
• Humans
• Liver Diseases (enzymology, genetics)
• Lymphocytes (enzymology)
• Mutation
• Phenotype
• Photosensitivity Disorders (enzymology, etiology, prevention & control)
• Polymorphism, Genetic
• Porphyria, Hepatoerythropoietic (complications, diagnosis, genetics)
• Protoporphyria, Erythropoietic
• Switzerland