Porphyria Educational Services
Porphyria Educational Services Bulletin Vol. 2 No. 40 October 8, 2000
FOCUS: Hereditary Coproporphyria [HCP]
Hereditary Coproporphyria is also known as HCP, Porphyria Hepatica, and Coproporphyria.
Hereditary Coproporphyria is an autosomal dominant form of hepatic porphyria that is very similar to Acute Intermittent Porphyria. While very much like AIP,it is usually a less severe disease.
Hereditary Coproporphyria is caused by an enzyme deficiency.
Some HCP patients develop skin photosensitivity, and must avoid sunlight.
The diagnosis of Hereditary Coproporphyria is established by finding excess coproporphyrin in urine and stool. Please note that other types of porphyrins show little or no increase. In HCP the urinary ALA and PBG are increased during acute attacks, but may become normal on recovery.
HCP is one of a group of at least eight disorders. The common feature in all porphyrias is the excess accumulation in the body of "porphyrins" or "porphyrin precursors." These are natural chemicals that normally do not accumulate in the body. Precisely which one of these porphyrin chemicals builds up depends upon the type of porphyria that a patient has. This is true of HCP.
Porphyrias can also be classified into two groups: the "hepatic" and "erythropoietic" types. Porphyrins and related substances originate in excess amounts from the liver in the hepatic types, and mostly from the bone marrow in the erythropoietic types.
The porphyrias with skin manifestations are sometimes called "cutaneous porphyrias." The "acute porphyrias" are characterized by sudden attacks of pain and other neurological manifestations. These acute symptoms can be both rapidly-appearing and severe. An individual may be considered in a "latent" condition if he or she has the characteristic enzyme deficiency, but has never developed symptoms. There can be a wide spectrum of severity between the "latent" and "active" cases of any particular type of this disorder. The symptoms and treatments of the different types of porphyrias are not the same.
The treatment for HCP parellels the current treatsments available for AIP. Additional treatment may be necessary to care for the cutaneous aspects of the HCP. Avoiding sunlight exposure or exposure to UV lighting is necessary.
Vance Little, PhD Professor of Molecular and Cell Biology