HomeGeneticsGeneCPOX gene
Back to Gene
CPOX gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CPOX gene

The CPOX gene provides instructions for producing an enzyme essential for heme production, and mutations in this gene are linked to specific forms of porphyria.

Overview

The CPOX gene provides instructions for making an enzyme known as coproporphyrinogen oxidase. This enzyme is involved in the production of a molecule called heme. Heme is vital for all of the body's organs, although it is most abundant in the blood, bone marrow, and liver. Heme is an essential component of iron-containing proteins called hemoproteins, including hemoglobin (the protein that carries oxygen in the blood).

The production of heme is a multi-step process that requires eight different enzymes. Coproporphyrinogen oxidase is responsible for the sixth step in this process, the removal of carbon and oxygen atoms from coproporphyrinogen III to form protoporphyrinogen IX. In subsequent steps, two other enzymes modify protoporphyrinogen IX and incorporate an iron atom to produce heme.

Health Conditions Related to Genetic Changes

Porphyria

At least 45 mutations in the CPOX gene have been found to cause porphyria. Mutations in this gene can cause two types of porphyria: hereditary coproporphyria and a variant known as harderoporphyria.

  • Most CPOX gene mutations change single protein building blocks (amino acids) in coproporphyrinogen oxidase.
  • A single mutation appears to be responsible for harderoporphyria; this genetic change replaces the amino acid glycine with the amino acid glutamic acid at position 404 (written as Lys404Glu or K404E).
  • Mutations in the CPOX gene reduce the activity of coproporphyrinogen oxidase, allowing compounds called porphyrins to build up in the body to toxic levels.
  • This buildup, in combination with nongenetic factors such as certain drugs, alcohol, and dieting, leads to the signs and symptoms of hereditary coproporphyria and harderoporphyria.

Other Names for This Gene

  • Coprogen oxidase
  • Coproporphyrinogen III oxidase, mitochondrial
  • Coproporphyrinogen III Oxidases
  • coproporphyrinogen oxidase (coproporphyria, harderoporphyria)
  • Coproporphyrinogen:oxygen oxidoreductase (decarboxylating)
  • Coproporphyrinogenase
  • COX
  • CPO
  • CPX
  • HCP
  • HEM6_HUMAN

Genomic Location

The CPOX gene is found on chromosome 3.

Frequently Asked Questions

Hereditary coproporphyria typically presents with abdominal pain, nausea, vomiting, constipation or diarrhea, and sometimes neurological symptoms such as muscle weakness, seizures, or psychiatric changes. Skin lesions may appear after sun exposure, and patients often report a sudden worsening of symptoms during periods of stress, illness, or after taking certain medications. If you notice a combination of these signs, especially if they come on suddenly, it may be worth discussing a porphyria work‑up with your clinician.
void known triggers: stay hydrated, maintain a regular eating schedule, avoid fasting, and steer clear of porphyrin‑inducing drugs (e.g., barbiturates, certain antibiotics, and some pain medications). Limit alcohol intake, avoid excessive sun exposure, and keep a list of safe foods and medications to share with your healthcare team. If you have a known CPOX mutation, having an emergency plan and carrying a medical alert card can help prevent or quickly treat attacks.
CPOX mutations are inherited in an autosomal dominant pattern, so each first‑degree relative has a 50 % chance of carrying the same mutation. Offer genetic counseling and testing to at-risk family members. If a relative tests positive, they should receive education on trigger avoidance, emergency management, and regular monitoring for early signs of porphyria.
DNA sequencing test (often part of a porphyria panel) will identify pathogenic variants in the CPOX gene. Prior to testing, avoid porphyrin‑inducing drugs for at least 48–72 hours, and inform your lab of any recent illnesses or medications. Blood samples are usually taken in the morning; fasting is not required unless your clinician specifies otherwise.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

kontakt@hittavard.se

Ⓒ 2024. Alla rättigheter förbehålls av juxt ab

Sök
Om ossVillkor och policyVanliga frågorKontakta oss