TPMT Genetic Testing
Thipurine methyltransferase is an enzyme that metabolizes medications located in the red blood cells, liver, kidney, and other tissues. TPMT plays a large role in the elimination of thipurine medications. This includes azathiprine (Imuran®), thiogaunine (Tabloid®), and mercaptopurine (Purixan®). These medications are commonly used to treat acute lymphoblastic leukemia, inflammatory bowel disease, organ transplant rejection, and autoimmune disorders. Like many enzymes, genetic mutations and variations can affect their activity. Impaired TPMT function can lead a patient to being a poor metabolizer of these medications. This can lead to myelosuppression. This is a condition where the bone marrow activity is decreased. This decreases the production or red blood cells, white blood cells, and platelets. A severe version of this condition is called myeloablation. It can lead to many life-threatening complications.
Genetic Testing for Leukemia Treatments
Prior to beginning any treatment that could be affected by TPMT metabolization issues, it is recommended that the patient receives a genetic test. This test can help medical providers predict and prevent issues like myelosuppression or myeloblastion. The relationship between these conditions and genetic variations that impact TPMT production has been studied. These studies have shown how variations could lead to life-threatening complications in leukemia treatments.
Patient Considerations for Pharamcogentic Testing
New studies in pharmacogenetics are being published every year. Over the last decade hundreds of prescription medications have been studied in relation to specific genes. Patients that are beginning a new treatment, are experiencing issues with a current treatment, or have family members that have experienced issues should consider pharmacogenetic testing. It is up to the clinical opinion of a medical provider to order these tests, however it is highly recommended for medications that are affected by the TPMT enzyme, as the side effects caused by poor reaction can be potentially life-threatening.