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Azathioprine (Thiopurine)

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Overview

Azathioprine is part of a class of drugs called 'thiopurines'

What is Azathioprine?
Azathioprine is part of a group of drugs called thiopurines. These drugs are widely used to treat leukemias and autoimmune disorders such as inflammatory bowel disease (Crohn's disease and ulcerative colitis) and arthritis. They are also used as immunosuppressants after organ transplantation.
As well as azathioprine the most common thiopurine drugs are mercaptopurine and thioguanine.

What is being tested?
A gene called TPMT (thiopurine S-methyltransferase) is involved in metabolizing azathioprine. Certain individuals have a genetic difference in a gene called TPMT, which means their body has problems processing the azathioprine. For these people, the drug can accumulate in the body, and become toxic.
Genetic testing allows us to identify these people prior to treatment, and therefore avoid this potentially negative reaction.

How will this affect my health care?
If testing shows that you may have a negative reaction to thiopurines such as azathioprine, you may be prescribed a different medication by your doctor.

If you have any questions about your test results or the medications you are on, please talk with your doctor.

You should follow your doctor's instructions on taking any medication. Do not change your medications on your own before speaking with your doctor.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Background

Why test for genetic interactions with azathioprine?
By performing a test on your DNA, we may be able to anticipate how you will respond to thiopurines and to adjust your treatment accordingly. The embedded video from the Children's Hospital of Philadelphia discusses how genetic testing of the TPMT gene can predict how you may respond to treatment with thiopurine drugs such as azathioprine.

How will this affect my treatment?
If genetic testing does indicate that you may not respond optimally to treatment with azathioprine, your doctor will likely change your prescription.

Can taking azathioprine cause any problems?
For the majority of people taking azathioprine will not cause any problems. However, in a small proportion of people, a change in medication may be recommended to prevent potentially toxic effects. These effects can include bleeding, sores, fever, red spots on the skin, yellowing eyes/skin, discolored urine and stool, bloody urine and stool.

Are any other complications associated with thiopurines?
Other complications include diarrhea, nausea, loss of appetite, tiredness, vomiting, loss of appetite, skin rash, pain, and hair loss.

Who is affected?Approximately 8% of people may have a genetic difference that affects how they metabolize azathioprine. Less than 1% of people may have a variant in the TPMT that may seriously affect their health if taking azathioprine.

Do different populations respond differently to azathioprine?
Genetic differences in azathioprine response are found in all populations.

Do reactions to azathioprine and other drugs run in my family?
We (typically) inherit two gene copies from each parent. If you have a genetic difference that affects how you respond to azathioprine, it is likely to have been inherited from one or both of your parents, and it is possible you will pass this to your children. However, this is not always the case, and a large variety of inheritance scenarios are possible. If you are concerned about this, we strongly advise you to discuss with your doctor or healthcare provider.

Is there a difference between being a carrier and being predisposed to a particular drug response?
You may carry a genetic a difference that does not affect how you respond to azathioprine, but may affect how your children might respond. A full discussion of the relevant scenarios/implications are beyond the scope of this site, however, and we recommend you discuss with your doctor or healthcare provider if this is a concern.

Why do genetic differences make people respond to azathioprine differently?
Azathioprine interacts with the TPMTgene in our body. Certain differences in the TPMT gene will make some people use azathioprine differently. For these people, the genetic difference means that taking azathioprine can be toxic and should be avoided.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Genetic Test

Weblink to Learn.Genetic Module, Making SNPs Make Sense

What is the test?
People react differently to medicine and some of those different reactions can be related to their genes. People with certain differences in their genes might not respond to particular medications as well as other people. The gene involved in how people use azathioprine is called, TPMT. This test will look for some of the genetic differences in the TPMTgene that can make people respond negatively to azathioprine.

What will the test result mean?
This test will tell your doctor whether you are likely to respond poorly to treatment with azathioprine, in which case an alternative course of medication will be recommended.

How is the test being performed?
Testing is performed on your DNA, usually extracted from a blood sample. For many patients, your hospital or treatment center may already have some of your DNA stored in a biobank. You may be asked for an additional sample or be asked to give us permission to do testing on the existing samples.

Will it hurt?
For some patients, we may need an additional blood sample. Taking blood may cause some pain, bleeding or bruising at the spot where the needle enters your body. Rarely, taking blood may cause fainting or infection.

Is it safe?
There is a risk that you may experience pain or bleeding if you need to give an additional blood sample. Risks concerning privacy are discussed under Privacy & Sharing.

How long will I have to wait for results?
Unfortunately, we cannot give an accurate estimate for the time you will have to wait for results - this will depend on the resources available at the center where you receive treatment.

Is this a standard test?
Although increasingly more common, this test is not yet standard, and is typically offered as part of a research study.

What type of test is this?
Is this test intended to confirm a diagnosis? No
Is this test intended to predict a family history of disease? No
Is this test intended to check if I am a carrier for a particular disease? No
Is this test intended to screen for genetic disorders? No
Is this test intended to screen for disorders related to pregnancy? No
Is this test intended to screen for disorders related to newborns? No

Will I need to have this test done more than once?
No, you should not need to have this test done more than once. You will need to keep track of your testing result in order to share with all of your doctors, including those you see at other medical care centers.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Treatment

How will this test affect my treatment?

For most people tested, it is likely that your treatment options will stay the same and that you will begin treatment with azathioprine using standard doses. If this is not the case, your doctor will either change your recommended dose or recommend a new treatment.

In the embedded video, Dr. Hakon Hakonarson (Children's Hospital of Philadelphia) explains that everyone does not respond in the same way to azathioprine, and responses may be related to your genetic make-up.

How will this result be used?

The result will be put into your medical record for your doctor to use when deciding about prescribing you azathioprine. Your doctor may:

  • Do other tests to see how you might respond to azathioprine
  • Do nothing and continue with your planned course of treatment
  • Change your dosage of azathioprine
  • Give you another medication that is not azathioprine to treat your condition
  • You should follow your doctor's instructions when taking any medication. Do not change your medications on your own before speaking with your doctor.

    Will I be referred to a specialist?
    It is unlikely that you will be referred to a specialist, but you may request an appointment with a genetic counselor.

    Is there anything else I should know?
    You should follow your doctor's instructions when taking any medication. Do not change your medications on your own before speaking with your doctor.

    More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

    Privacy & Sharing

    Should I tell other healthcare providers about my test result?
    If your doctor who prescribes medication for you doesn't already know about your test result, we do recommend that you share this information with him/her. However, as explained by Maureen Smith (Nortwestern University) in the embedded video, what you decide to do with your results is up to you.

    Who will see my test results?
    People who have access to your medical record will be able to see your genetic test result. This may include health professionals such as doctors, nurses, pharmacists, and genetic counselors. However, health professionals from other centers or hospitals will likely not have access to your results.

    Should I tell other healthcare providers about my test result?
    If your doctor who prescribes medication for you doesn't already know about your test result, you should share this information with him/her.

    Should my other family members be tested to see how they might respond to thiopurines?
    You may want to share your test results with your family, since they might have the same genetic variant as you.

    Will this affect my health insurance?
    No, your health insurance will not be affected by this azathioprine test result.

    Who can I contact if they have any more questions?
    You can contact your local center, where you received the test. We have also included a recommended list of resources in the Videos & More tab to the right.

    Is it there a risk to my privacy?
    Research that uses information from medical records and that involves genetic testing can affect your privacy. Your participation in this research will be held strictly confidential, and only coded numbers will be used to identify specimens and research records. While it is impossible to absolutely guarantee that information in our secure system will never be known by others, we are taking every possible precaution to see that this does not happen.

    More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

    Risks

    What Should I Do If I Have Concerns About Genetic Test Results?
    If you are concerned about genetic test results you have received, you should discuss your concerns with your doctor. Your doctor should be able to explain results to you, and may recommend you to a genetic counselor or another doctor that can further help you understand your results. Maureen Smith (Northwestern University) discusses these concerns in the embedded video/

    Is there a reason why I may be a specific risk?
    Testing is recommended for all individuals undergoing or considering undergoing treatment with azathioprine.

    Are there any implications for having children?
    No.

    If I am found to have a specific gene variant, am I at increased risk?
    For some individuals, there gene test result may indicate that they are at an increased risk of responding poorly to azathioprine. Testing is done to help guide your doctor chose the best treatment for you.

    Can I expect to experience emotional consequences related to my test result?
    A range of reactions are possible and normal. Some patients may experience anxiety or other negative reactions related to their use/potential use of azathioprine. If this is the case, please discuss with your doctor, who can address your concerns and refer you another health professional if required.

    Can I expect to experience social consequences related to my test result?
    We do not anticipate any social consequences related to use/potential use of azathioprine. As always however, if you do experience any negative social reactions, please discuss with your doctor who can address your concerns.

    Can I expect to experience an increase in anxiety?
    Many individual experience increased anxiety related to genetic testing. Again, please discuss with your doctor if this is the case.

    Are there any implications in terms of discrimination arising from the test result?
    Health insurance companies are prevented by law from discriminating against you based on your genetic test results. However, the same law does not apply to long-term disability insurance or to life insurance.

    If I am found to be at increased risk for responding poorly to azathioprine, are there similar health implications for my family?
    If results indicate that you may respond poorly to azathioprine, your family may be more likely to have a similar response should azathioprine ever be considered an option for them. As such, you may want to discuss your results with your family.

    Are there likely to be emotional consequences relevant to azathioprine for my family?
    Similar to patients, family members may experience a range of reactions, which is normal. We recommend that if you discuss any questions or problems with your healthcare provider.

    More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

    Videos & More

    Dr. Dan Roden explains that if you give the same dose of a drug to a large number of people, responses will vary. Some people will have a great response, some will have no response, while others will experience adverse side effects. Some of this variability resides in our genes. The science of pharmacogenetics is the science of trying to understand the genes that contribute to the variability of drug action.

    You can view more videos at our Resources section.

    RECOMMENDED WEBSITES

    Find a Genetic Counselor directory developed by the National Society of Genetic Counselors.

    Genetics Home Reference has basic information about genetics and links to other resources about genetics.

    Medline Plus has more information about azathioprine, other drugs, and other health conditions.

    Lab Tests Online provides patient-centered reviews about lab testing and drug products.

    Daily Med provides high quality information about marketed drugs.

    The Pharmacogenomics Knowledge Base is a resource for medical professionals about how variation in human genetics leads to variation in response to drugs.

    About

    Are there geographical differences in service or treatment related to thiopurines?
    Different centers have different policies in terms of how tests are administered and results shared. However, the results discussed in this document should be relevant to most individuals tested for thiopurine-gene interactions.

    How is this paid for?
    If you received this test as part of the eMERGE research study, neither you nor your insurance company will have to pay anything toward this test

    When was this content last updated?
    January 15, 2014.

    More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.
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