Porphyria

AIP is caused by the deficiency of an enzyme called porphobilinogen deaminase (PBGD), also known as hydroxymethylbilane synthase (HMBS) and formerly known as uroporphyrinogen I-synthase. The deficiency of PBGD is caused by a mutation in the HMBS gene. The HMBS gene is the only gene known to be associated with AIP. However, the deficiency of PBGD alone is not enough to cause AIP. Other activating factors (e.g., hormones, drugs, dietary changes) must also be present.

Genetic studies have linked Chester porphyria to a gene located on the long (q) arm of chromosome 11.

Some of the activating factors include :

• Drugs (e.g., barbiturates, aluminum hydroxide, tricyclic antidepressants, alcohol)
• Smoking
• Surgery
• Metabolic abnormalities such as low levels of sodium (hyponatremia)

Many of the signs and symptoms of porphyria are similar to those of other more common diseases. Also, because porphyria is rare, many doctors have not seen cases of the disorder before, making it more difficult to diagnosis. Because porphyria's signs and symptoms usually aren't distinctive, laboratory tests are required to make a definitive diagnosis and to determine which type of porphyria is involved.

If your doctor suspects porphyria, he or she may recommend the following tests:

• Urine test. If you have a form of acute porphyria, a urine test may reveal elevated levels of two substances: porphobilinogen and delta-aminolevulinic acids, as well as other porphyrins.
• Blood test. If you have a form of cutaneous porphyria, a blood test may show an elevation in the level of porphyrins in the liquid part of your blood (plasma).
• Stool sample test. Analysis of a stool sample may reveal elevated levels of some porphyrins that may not be detected in urine samples. This test may help your doctor determine your specific type of porphyria.

Genetic testing may also be used to confirm the diagnosis.

Yes. Genetic Testing Registry (GTR) lists laboratories offering clinical genetic testing for several types of porphyria. Clinical genetic tests are ordered to help diagnose a person or family and to aid in decisions regarding medical care or reproductive issues. Talk to your health care provider or a genetic professional to learn more about your testing options.

Although the gene that causes Chester porphyria has not been identified, the condition is believed to be inherited in an autosomal dominant manner.

AIP is inherited in an autosomal dominant fashion, which means only one of the two HMBS genes needs to have a disease- causing mutation to decrease enzyme activity and cause symptoms.

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by GeneTests, the American College of Medical Genetics, and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.

Acute intermittent porphyria (AIP) is one of the liver (hepatic) porphyrias. AIP is caused by low levels of porphobilinogen deaminase (PBGD), an enzyme also often called hydroxymethylbilane synthase. The low levels of PBGD are generally not sufficient to cause symptoms; however, activating factors such as hormones, drugs, and dietary changes may trigger symptoms. Although most individuals with AIP never develop symptoms, symptomatic individuals typically present with abdominal pain with nausea. Treatment is dependent on the symptoms.

Chester porphyria is a unique type of porphyria with the signs and symptoms of acute intermittent porphyria (AIP) and the biochemical defects of both AIP and variegate porphyria (VP). Chester porphyria does not conform to any of the recognized types of acute porphyria. The symptoms associated with Chester porphyria are similar to those observed in other acute porphyrias. Treatment is symptomatic.

Porphyrias are a group of blood conditions caused by a lack of an enzyme in the body that makes heme, an important molecule that carries oxygen throughout the body and is vital for all of the body’s organs. Major types include ALAD deficiency porphyria, acute intermittent porphyria, congenital erythropoietic porphyria, erythropoietic protoporphyria, hepatoerythropoietic porphyria, hereditary coproporphyria, porphyria cutanea tarda, and variegate porphyria. The most common type of porphyria is porphyria cutanea tarda. Some of the symptoms of porphyria include blistering, swelling, and itching when the skin is exposed to sun. Other symptoms may also include pain, numbness or tingling, vomiting, constipation, and intellectual disability. There is no known cure for porphyria, but the various types have different courses of treatment, and may include bone marrow transplant.

Most porphyrias are inherited conditions with either an autosomal dominant or autosomal recessive pattern of inheritance. However, some forms of porphyria can be caused by environmental factors such as infections or exposures to certain prescription drugs. Porphyrias caused by environmental factors are called sporadic or acquired porphyria.

The goal of management is to avoid activating factors. Treatment is symptomatic.

Treatment of AIP may vary based on the trigger of the attack and the symptoms present. Treatment may include stopping medications that cause or worsen the symptoms, treating any infections which may be present, administration of pain medication, monitoring fluid balance and/or correcting electrolyte disturbances, monitoring neurologic status and administering respiratory support. Mild attacks can be manged with increased caloric intake and fluid replacement. Recurrent acute attacks should be managed by a porphyria specialist. Hospitalization is often necessary. Panhematin, an intravenous medication used to correct heme deficiency, may also be prescribed. More detailed information about the use of Panhematin for the treatment of AIP can be found by clicking here.