Hereditary Coproporphyria (HCP)


Hereditary coproporphyria (HCP) is caused by a defect in the CPOX gene which codes for mitochondrial coproporphyrinogen-III oxidase. A defect in this enzyme results in accumulation of the porphyrin precursors porphobilinogen and 5-aminolevulinic acid; increase of fecal and urinary excreation of coproporphyrins. Symtpoms include reddish-purple urine, acute neurological problems (typically episodic confusion and sensory changes), and attacks of acute abdominal/nerve pain. Around 30% suffer photosensitive skin eruptions with nail involvement; these can lead to permanent scarring. While there is no cure for this condition, there are preventative measures people can take to regulate symptoms. A diet high in carbohydrates, glucose, as well as avoidance of aggravating factors (such as alcohol and drug use) can prevent attacks.

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References

  1. Uniprot: P36551
  2. OMIM: Entry 121300
  3. Andrews J, Erdjument H, Nicholson DC: Hereditary coproporphyria: incidence in a large English family. J Med Genet. 1984 Oct;21(5):341-9. Pubmed
  4. Barohn RJ, Sanchez JA, Anderson KE: Acute peripheral neuropathy due to hereditary coproporphyria. Muscle Nerve. 1994 Jul;17(7):793-9. Pubmed
  5. Gross U, Puy H, Meissauer U, Lamoril J, Deybach JC, Doss M, Nordmann Y, Doss MO: A molecular, enzymatic and clinical study in a family with hereditary coproporphyria. J Inherit Metab Dis. 2002 Aug;25(4):279-86. Pubmed
  6. Lamoril J, Martasek P, Deybach JC, Da Silva V, Grandchamp B, Nordmann Y: A molecular defect in coproporphyrinogen oxidase gene causing harderoporphyria, a variant form of hereditary coproporphyria. Hum Mol Genet. 1995 Feb;4(2):275-8. Pubmed