Your QuestionI would like to be tested for porphyria. How is this condition diagnosed? Is genetic testing available?
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Most porphyrias are inherited conditions with either an autosomal dominant or autosomal recessive pattern of inheritance. Porphyria can also be caused by environmental factors such as infections or exposures to certain prescription drugs. This type of porphyria is called sporadic or acquired porphyria.
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.
Some of the other tests that may be done include:
Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.
The following online resources can help you find a genetics professional in your community:
- The National Society of Genetic Counselors provides a searchable directory of US and international genetic counseling services.
- The American College of Medical Genetics has a searchable database of US genetics clinics.
- The University of Kansas Medical Center provides a list of US and international genetic centers, clinics, and departments.
- The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.
- Porphyria. National Digestive Diseases Information Clearinghouse (NDDIC). 2008; http://digestive.niddk.nih.gov/ddiseases/pubs/porphyria/index.htm. Accessed 6/27/2011.
- Dugdale DC, Chen YB. Porphyria. MedlinePlus. 2009; http://www.nlm.nih.gov/medlineplus/porphyria.html. Accessed 6/27/2011.
- Porphyria. Genetics Home Reference. 2009; http://ghr.nlm.nih.gov/condition=porphyria. Accessed 6/27/2011.
- Porphyria. MayoClinic.com. 2009; http://www.mayoclinic.com/health/porphyria/DS00955/METHOD=print. Accessed 7/24/2009.