[1] HCP is caused by a deficiency of the enzyme coproporphyrinogen oxidase, coded for by the CPOX gene, and is inherited in an autosomal dominant fashion, although homozygous individuals have been identified.

This enzyme is responsible for the sixth step in the heme biosynthetic pathway, converting coproporphyrinogen III to protoporphyrinogen IX.

[1] Along with other acute porphyrias HCP demonstrates reduced penetrance, meaning not all individuals who carry a disease-causing mutation will express symptoms.

[2] Individuals who are homozygous for a specific mutation (K404E) or compound heterozygous with a null allele in CPOX have a more severe erythropoietic porphyria, harderoporphyria,[5] characterized by neonatal jaundice, hyperbilirubinemia, hepatosplenomegaly and skin lesions upon exposure to ultraviolet light.

[6] HCP is a rare disease, but the exact incidence is difficult to determine due to the reduced penetrance of the acute porphyrias.

Bedside measurement of urine porphobilinogen is recommended as a screening test for patients suspected of having an acute porphyria.

[3][7] The identification of a specific porphyria is based on the results of laboratory findings, including blood, urine and stool tests.

VP presents similarly, but can be distinguished based on urine and stool porphyrin analysis, typically done using high performance liquid chromatography with fluorescence detection.

Coproporphyrinuria can be caused by other stressors to the heme biosynthetic pathway, such as liver disease, lead poisoning and certain bone marrow disorders.

[3] Proper drug selection is most difficult when it comes to treatment of the seizures that can accompany HCP, as most anti-seizure medications can make the symptoms worse.