Hepatic porphyria

Hepatic porphyria is a group of rare, genetic disorders characterized by problems in the production of heme, a vital component of hemoglobin, the protein in red blood cells that binds and carries oxygen. These disorders are termed "hepatic" because the liver is the primary site of the disturbance in heme production. Porphyrias are classified based on where the production of heme is disrupted: in the liver (hepatic) or in the bone marrow (erythropoietic). Hepatic porphyrias lead to the accumulation of porphyrins or porphyrin precursors, substances that are normally intermediates in the production of heme, causing a variety of symptoms.

Types of Hepatic Porphyria

There are several types of hepatic porphyria, each with its own specific symptoms and genetic causes. The most common types include:

• Acute Intermittent Porphyria (AIP)
• Porphyria Cutanea Tarda (PCT)
• Hereditary Coproporphyria (HCP)
• Variegate Porphyria (VP)

Symptoms

Symptoms of hepatic porphyria can vary widely among individuals and between the different types of porphyrias. They can be categorized into two main groups: acute (neurovisceral) symptoms and cutaneous (skin) symptoms.

Acute Symptoms

Acute symptoms are primarily neurological and can be severe. They include:

• Abdominal pain
• Vomiting
• Neuropsychiatric symptoms, such as anxiety, confusion, hallucinations, or depression
• Seizures
• Muscle weakness or paralysis

Cutaneous Symptoms

Cutaneous symptoms occur due to the skin's sensitivity to sunlight and can include:

• Blisters
• Itching
• Swelling
• Increased hair growth on the affected area
• Scarring

Diagnosis

Diagnosis of hepatic porphyria involves a combination of clinical evaluation, family history, and specialized laboratory tests that measure porphyrins and their precursors in blood, urine, and stool.

Treatment

Treatment for hepatic porphyria focuses on managing symptoms and preventing acute attacks. This may include:

• Avoiding triggers such as certain drugs, alcohol, and fasting
• Treatment with heme arginate or hemin for acute attacks
• Phlebotomy or low-dose chloroquine for PCT to reduce iron and porphyrin levels

Genetics

Hepatic porphyrias are inherited in an autosomal dominant manner, meaning a mutation in just one of the two copies of the gene is sufficient to increase the risk of developing the disorder. However, not all individuals with a mutation will experience symptoms, a phenomenon known as incomplete penetrance.

Prevention

Preventive measures for those with hepatic porphyria or at risk include avoiding known triggers, regular monitoring for symptoms, and genetic counseling for affected families.