Porphyrias are rare genetic diseases characterized by the accumulation of porphyrins, metabolites used in the synthesis of the heme molecule. These accumulations can be responsible for a large number of symptoms.
Definition: what is porphyria?
Porphyrias are rare genetic diseases that manifest as presence in the body of heme precursor molecules, found in urine, blood and stool. “The porphyrias are classified in two different ways: a first classification separates the porphyrias according to the place of initial accumulation of the molecules, we then speak of hepatic porphyrias (or porphyrias of the liver) or erythropoietic porphyrias (porphyrias of the bone marrow) ; another classification separates the porphyrias according to the symptoms: porphyrias with cutaneous expression and porphyrias causing attacks of abdominal pain. Among the latter, some are said to be mixed and can therefore also give skin symptoms.explains a doctor from the Reference Center for Rare Porphyria Diseases, who wishes to remain anonymous
What are the causes of cutaneous porphyria?
This disease is caused by a partial deficiency in the activity of an enzyme called Uroporphyrinogen decarboxylase (UROD). This leads to a accumulation of porphyrins in the liver which then pass into the blood and then into the skin. “These porphyrins react to exposure to light”, says the expert. Cutaneous symptoms usually begin during adult life, hence the term “late” that is sometimes encountered. “There are most often triggering factors such as regular alcohol consumption, excess fat in the liver, viral infections of the liver (including hepatitis C) and treatment with estrogen. We sometimes find a genetic alteration favoring the occurrence of the pathology“, adds the expert.
What causes acute intermittent porphyria?
It is the most common form of acute hepatic porphyria. It is due to a porphobilinogen deaminase enzyme deficiency (also called hydroxymethylbilane synthase), which causes an accumulation of the porphyrin precursors delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) in the liver.
What are the symptoms of a porphyria attack?
It all depends on its location. “The main symptom of an attack of acute hepatic porphyria is the occurrence of severe, prolonged abdominal pain (several days), in contine“says the center’s expert. Other symptoms may occur depending on the type of porphyria:
- Of the nausea and vomiting, constipation
- A type of nerve damage transient paralysis or sensory disturbances;
- Of the psychiatric disorders passengers in certain acute porphyrias.
- We frequently find port-colored urine, after exposure to light.
Diagnosis of porphyria is made through a urine analysis (for porphyrias responsible for porphyria attacks) or a blood test (for porphyrias with cutaneous expression). The aim is to detect the presence of porphyrins or their precursors.
What treatment to treat porphyria?
There is no curative treatment. But it is possible to treat the various symptoms. In the event of a major crisis, analgesics associated with an intravenous supply of glucose are recommended in certain forms of acute porphyria. Generally, the acute attack disappears spontaneously in a few days. However, some symptoms may persist long after the illness has ended. Treatment of these is then necessary. “However, in severe forms, a preventive treatment for seizures is now available“, specifies our expert. In the event of cutaneous porphyria, it is possible to set up a treatment that promotes the excretion of excess porphyrins and drugs that reduce skin sensitivity.
Thank you Porphyrias Rare Diseases Reference Center.