Hereditary coproporphyria

Abstract

Hereditary coproporphyria (HC) is a rare acute hepatic porphyria. Attacks may be precipitated by certain drugs, alcohol, infections, or low caloric intake. HC is caused by defects in the enzyme coproporphyrinogen III oxidase (copro-ox) which converts coproporphyrinogen III (coprogen) to protoporphyrinogen IX (protogen). Coprogen is made mainly in the liver and is excreted predominantly in the feces. The dramatic increase in coproporphyrin III (copro) excretion (10-200 times compared with the control value) with intensive red fluorescence under UV light is a specific and easily detectable marker for diagnosis of acute attacks of HC. HC is inherited as an autosomally dominant genetic defect. The cDNA and gene encoding copro-ox have been isolated recently and mutations have been identified, providing critical information concerning molecular heterogeneity and the potential for molecular diagnosis. In this review, we describe 10 mutations in the copro-ox gene which are spread along six exons. It is postulated that DNA analysis of gene carriers and the use of heme arginate for specific treatment will improve the care of HC patients dramatically.