Genetic Counseling for Porphyria
Porphyria is the name given to a set of rare genetic disorders that can affect the nervous system (acute prophyria), the skin (cutaneous), or both.
Genetic counseling can help you learn more about your disease type, and help to guide you in understanding how the disease might affect your life and that of your family.
Genetics of porphyria
Porphyria is a group of similar but distinct genetic disorders. Mutations in one of eight genes cause its differing types. These genes all play a role in the process of making heme. Heme is a major component of hemoglobin in red blood cells, which carries oxygen throughout the body. Porphyrins are the precursors of heme. Mutations in one of the genes causing porphyria can result in porphyrins to build in tissues and organs. This can lead to the symptoms of porphyria.
Some of the mutations that cause porphyria are inherited in a dominant pattern. This means that having only one copy of the mutated gene can cause the disease. Alternatively, they can be inherited in a recessive pattern. In this case, patients most likely will not have symptoms unless they receive a faulty copy of the gene from each parent. The mutations can also be sex-linked or autosomal depending on whether the faulty gene is on the X chromosome or on one of the other 22 pairs of chromosomes, respectively.
What is genetic counseling?
Genetic counseling involves speaking with a genetic counselor or another healthcare professional who can help you understand more about a particular genetic disorder. They can talk to you about the inheritance of the disease, the type of testing to diagnose it, and how the disease could affect your life.
A genetic counselor will usually analyze your personal and family health history. They will ask about your symptoms and any test results you might already have had. They can then calculate the odds of you potentially having a form of porphyria. Based on this information, you can decide whether you would like to undergo further diagnostic testing, such as genetic testing.
If you have already had a genetic test, a genetic counselor will discuss its results with you, and what follow-up testing you may need. The counselor can also help to put test results into practical terms, including what they mean for your life ahead.
When might I need genetic counseling?
There are several reasons you might want to speak with a genetic counselor. If you are planning to have children but you have porphyria or porphyria runs in your family, you can speak with a counselor about the risk of your children inheriting the disease. You might also want guidance if you are already expecting a child, and have a family history of porphyria.
Another important time to speak to a genetic counselor is if you or your child are experiencing symptoms of porphyria. This can help you learn more about the disease, and decide if further testing is necessary.
A porphyria diagnosis for you or a family member can also be a good time to meet with a genetic counselor. The counselor will help you understand the disease’s cause and its possible affects on your life moving forward. They can also work with your physician to help you decide on treatment options to manage the disease and its symptoms. If a family member tests positive, genetic counseling can help you decide if you should also undergo a test.
What if I test positive for porphyria?
If you test positive for porphyria, you will want to meet with your physician and genetic counselor. They will discuss your test results with you and the next steps.
They will also discuss possible symptoms, your treatment options, and likely effects of your diagnosis on your life. For example, they could advise you to avoid sunlight if you have one of the cutaneous (skin) porphyrias. They could also talk to you about medications to avoid if you have acute porphyria.
A genetic counselor can also help you to find a support network that can give you encouragement and advice on how to live with porphyria. Some organizations help in searches for doctors with expertise in treating porphyrias.
What if test results are negative?
After a negative genetic test for porphyria, you may want to meet with a genetic counselor to discuss other conditions that could be causing your symptoms, and additional tests to consider.
You may feel anxious, sad, or depressed — a type of “survivor’s guilt” — especially if another family member has tested positive. If you are experiencing any of these feelings, you should discuss them with your physician, genetic counselor, or therapist.
Last updated: Nov. 24, 2020
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