Porphyria (cont.)

Most porphyrias are inherited disorders, meaning they are caused by abnormalities in genes passed from parents to children. Scientists have identified the genes for all eight enzymes in the heme pathway. Some forms of porphyria result from inheriting an abnormal gene from one parent. Other forms are due to inheriting two abnormal genes -- one from each parent. The risk that members of an affected family will have the disease or transmit it to their children depends on the type of porphyria.

One type of porphyria -- porphyria cutanea tarda -- is most often an acquired disorder. It occurs when factors other than genes cause an enzyme deficiency in the liver.

Porphyria can be triggered by:

• Drugs such as barbiturates, tranquilizers, birth control pills, and sedatives
• Chemicals
• Fasting
• Smoking
• Drinking alcohol, especially heavy drinking
• Infections
• Excess iron in the body
• Emotional and physical stress
• Menstrual hormones
• Exposure to the sun

People with cutaneous forms of porphyria develop blisters, itching, and swelling of their skin when it is exposed to sunlight. Symptoms of acute forms of porphyria include pain in the abdomen, chest, limbs, or back; numbness, tingling, paralysis, or cramping; vomiting; constipation; and personality changes or mental disorders. Acute attacks of porphyria can develop over hours or days and last for days or weeks.

Symptoms can vary widely in severity. Some people with gene mutations that can cause porphyria have no signs or symptoms of the disorder. These people are said to have latent porphyria.

Source: MedicineNet.com
http://www.medicinenet.com/porphyria/article.htm