Hereditary Coproporphyria

Updated: Jan 21, 2015
  • Author: Thomas G DeLoughery, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Overview

Background

Hereditary coproporphyria is one of the porphyrias, a group of diseases that involves defects in heme metabolism and that results in excessive secretion of porphyrins and porphyrin precursors. Inheritance is autosomal (usually autosomal dominant, but sometimes autosomal recessive).

Many persons with the disorder remain asymptomatic. Attacks may be triggered by chemicals (including many medications) or situations (eg, fasting) that boost heme synthesis. Coproporphyria manifests with signs and symptoms that include abdominal pain, neuropathies, constipation, and skin changes.

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Pathophysiology

Coproporphyria is an autosomal dominant disease that results from defects in the enzyme coproporphyrinogen oxidase. This enzyme speeds the conversion of coproporphyrinogen to protoporphyrinogen. In coproporphyria, the porphyrin precursors porphobilinogen and amino-levulinic acid (ALA) accumulate, as well as the formed porphyrin coproporphyrin. The predominant problem is neurologic damage that leads to peripheral and autonomic neuropathies and the psychiatric manifestations. In coproporphyria, skin disease also is present but not as commonly as the neurovisceral symptoms.

The etiology of the skin disease may be the deposition of formed porphyrins in the skin that react with sunlight and lead to skin damage. Although patients with acute neurovisceral attacks always have elevations of porphobilinogen and ALA, researchers still are unclear about how this leads to the symptomatic disease because most patients with the genetic defect have excessive porphyrin secretion but no symptoms. [1]

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Epidemiology

Frequency

United States

Coproporphyria is 20 times less common (ie, 1-4 cases per 1,000,000 people) than AIP.

Mortality/Morbidity

Researchers feel that coproporphyria is a less severe disease than AIP, but deaths have been reported in improperly treated cases.

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Sex- and Age-based Demographics

Researchers feel that women with coproporphyria tend to be symptomatic more than men are, but the data are sparse.

Most patients with porphyria become symptomatic at age 18-40 years. Attacks are rare before puberty or after age 40 years.

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