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Hereditary coproporphyria


Other Names for this Disease

  • Coproporphyria
  • Coproporphyria hereditary
  • Coproporphyrinogen oxidase deficiency
  • CPO deficiency
  • CPRO deficiency

Related Diseases

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Overview

What is hereditary coproporphyria?

What symptoms may be associated with hereditary coproporphyria?

What causes hereditary coproporphyria?

What is hereditary coproporphyria?

Hereditary coproporphyria is an autosomal dominant form of liver (hepatic) porphyria that is very similar to acute intermittent porphyria, although it is usually a less severe disease.[1] It results from low levels of the enzyme responsible for the sixth step in heme production - coproporphyrinogen oxidase.[2][3] 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. This leads to abdominal pain, neuropathies, constipation, and skin changes.[3] Treatment is dependent on the symptoms.[4]
Last updated: 11/11/2010

What symptoms may be associated with hereditary coproporphyria?

Most patients with defects in coproporphyrinogen oxidase never have any symptoms.[3] When symptoms do present, hereditary coproporphyria shows itself in 2 ways, as "acute attacks" and as skin problems.[5] 

Acute attacks are characterized by abdominal pain, nausea, vomiting and loss of appetite. These symptoms are often accompanied by constipation and a fast pulse rate. The urine of individuals experiencing an attack may be dark or it may darken on standing, particularly in sunlight. In rare cases, changes in the level of consciousness and various abnormalities of mental function may occur along with muscle weakness which may become life-threatening.[5] Between acute attacks, individuals are often symptom free.[3]
 
The skin manifestations are similar to those in porphyria cutanea tarda. Blisters form in sun-exposed areas and can evolve into chronic scarred areas of fragile skin. Patients also may develop excessive hair growth in sun-exposed areas.[3]
Last updated: 11/11/2010

What causes hereditary coproporphyria?

Hereditary coproporphyria is due to a combination of a genetic enzyme defect and acquired causes that become symptomatic in rare cases. In patients with coproporphyria, the function of coproporphyrinogen oxidase is only 40-60% of normal. Most patients with defects in coproporphyrinogen oxidase never have any symptoms. The classic inducers of porphyria are chemicals or situations that boost heme synthesis. This includes fasting and many medications.[3] Tables which list medications which are safe and unsafe can be accessed by clicking here.

The deficient enzyme in hereditary coproporphyria is coproporphyrinogen oxidase, which is responsible for the sixth step in heme production.[1][2][3][4] 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.[3]

The predominant problem is neurologic damage that leads to peripheral and autonomic neuropathies and the psychiatric manifestations. Skin disease may also be present, though not as often 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.[3]
Last updated: 11/11/2010

References
  1. Porphyria, Hereditary Coproporphyria. National Organization for Rare Disorders (NORD). 2007; http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Porphyria%2C%20Hereditary%20Coproporphyria. Accessed 11/11/2010.
  2. Learning about Porphyria. National Human Genome Research Institute (NHGRI). 2010; http://www.genome.gov/19016728. Accessed 11/11/2010.
  3. DeLoughery TG. Porphyria, Hereditary Coproporphyria. eMedicine. 2009; http://emedicine.medscape.com/article/205374-overview. Accessed 11/11/2010.
  4. Hereditary Coproporphyria (HCP). American Porphyria Foundation. 2009; http://www.porphyriafoundation.com/about-porphyria/types-of-porphyria/HCP. Accessed 11/11/2010.
  5. Hereditary Coproporphyria. Canadian Porphyria Foundation. http://www.cpf-inc.ca/HCP.htm. Accessed 11/11/2010.


Other Names for this Disease
  • Coproporphyria
  • Coproporphyria hereditary
  • Coproporphyrinogen oxidase deficiency
  • CPO deficiency
  • CPRO deficiency
Related Diseases
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.