Hereditary coproporphyria

Hereditary coproporphyria is a rare inherited disorder of porphyrin metabolism, part of a group of conditions called porphyrias, caused by a partial deficiency of a specific enzyme involved in producing haem, a component of haemoglobin. It can cause acute attacks of abdominal pain and neurological symptoms, as well as, less commonly, skin sensitivity to light. Attacks can be triggered by certain medications, alcohol, hormonal changes, or fasting.

It is caused by inherited mutations affecting the enzyme coproporphyrinogen oxidase, involved in the pathway that produces haem. It is inherited in an autosomal dominant pattern, though not everyone who carries the gene mutation develops symptoms (incomplete penetrance). Attacks are often triggered by specific factors such as certain medications, alcohol, fasting, infection, or hormonal changes, particularly in women.

Acute attacks typically cause severe abdominal pain, alongside symptoms such as nausea, vomiting, constipation, and sometimes neurological symptoms including weakness, confusion, or seizures in severe cases. A minority of people also experience skin sensitivity to sunlight, causing blistering or fragility, which is somewhat distinctive to this specific type of porphyria compared with some others. Between attacks, many people have no symptoms at all.

Yes, acute attacks can be serious, with severe cases potentially causing significant neurological complications, including paralysis, if not promptly recognised and treated. With prompt diagnosis, avoidance of known triggers, and appropriate treatment during attacks, most people manage the condition well with infrequent or milder episodes. Because acute porphyria attacks can be life-threatening, they need urgent hospital assessment when they occur.

Diagnosis involves specific urine, stool, and blood tests looking for abnormal porphyrin metabolites, ideally collected during or shortly after an acute attack when levels are most likely to be abnormal. Genetic testing can confirm the specific underlying mutation and help identify affected family members. Because porphyria is rare and its symptoms can mimic other conditions, diagnosis is sometimes delayed unless specifically considered.

Acute attacks are treated in hospital with intravenous haem arginate, which helps reduce the abnormal build-up of porphyrin precursors, alongside supportive care for pain and other symptoms. Avoiding known trigger factors, including certain medications, alcohol, and prolonged fasting, is central to preventing future attacks. A specialist porphyria centre can provide a detailed list of medications and other factors to avoid, tailored to this specific type of porphyria.

There is no cure for the underlying genetic enzyme deficiency, but careful trigger avoidance and prompt treatment of any attacks that do occur allow most people to manage the condition well and lead largely normal lives. Some people experience very few or no attacks throughout their life despite carrying the genetic mutation. Ongoing specialist follow-up helps manage the condition and adjust advice as needed over time.

Both are types of acute porphyria causing similar attacks of severe abdominal pain and neurological symptoms, triggered by similar factors, but they are caused by deficiencies in different specific enzymes in the haem production pathway. Hereditary coproporphyria can additionally cause skin sensitivity to light in some patients, which is not typically a feature of acute intermittent porphyria. Specific biochemical and genetic testing distinguishes between the different types of acute porphyria, which is important for accurate genetic counselling and, in some cases, choosing the most appropriate specific treatment.

Seek urgent hospital assessment for severe abdominal pain, particularly with vomiting, constipation, or any neurological symptoms, especially if you have a known diagnosis or family history of porphyria. If newly suspected without a known diagnosis, mention any relevant family history to the assessing doctor to help guide appropriate testing. Ongoing specialist follow-up at a porphyria centre, once diagnosed, can typically be arranged and is important for long-term trigger-avoidance advice and monitoring.