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