Coproporphyria

Inheritance:

Autosomal dominant

Frequency:

Approximately 1-4 in 1,000,000

Locus:

3q12

Natural History

Coproporphyria is due to a combination of an enzyme deficiency and environmental triggers. Affected individuals typically have between 40 — 60% coproporphyrinogen oxidase activity. The majority of individuals with a deficiency are asymptomatic. Chemicals or situations that cause a demand for heme, increasing heme production, can induce the phenotype. In general, drugs that utilize the hepatic P450 system induce porphyria. Onset of symptoms generally begins between 18-40 years of age.

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Defining characteristics:

Gastrointestinal

Abdominal pain, constipation, vomiting, neonatal hepatosplenomegaly

Skin

Neonatal jaundice, photosensitivity that can produce bullae, chronic scarred areas of fragile skin, and excessive hair growth

Neurologic

Seizures, cortical blindness, coma

Peripheral neuropathies with weakness beginning in the lower limbs and ascending, diffuse pain in the upper body

Autonomic neuropathies including hypertension and tachycardia

Other

Hemolytic anemia

Coproporphyrinogen oxidase deficiency, excessive amounts of coproporphyrin III in feces and urine, increased hepatic delta-aminolevulinic acid synthetase, during attacks increased urinary porphobilinogen and delta-aminolevulinic acid levels

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Psychiatric Characteristics

Depression, psychosis, hysteria, delirium

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References:

Crimlisk, H.L. The little imitator-porphyria: a neuropsychiatric disorder. Journal of Neurology, Neurosurgery and Psychiatry 62: 319-328 (1997).

eMedicine

http://www.emedicine.com/med/topic1888.htm

OMIM

http://www.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?121300

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