Living with Thiopurine S-methyltransferase deficiency
An inherited condition in which the body has low activity of an enzyme that processes thiopurine drugs.
Understanding Thiopurine S-methyltransferase deficiency
Thiopurine drugs suppress the immune system and are used for some autoimmune diseases, some blood cancers, and after organ transplants. People with TPMT deficiency are at highest risk of bone marrow damage from these drugs. This can lead to anemia, low white blood cells, and low platelets. Many health care providers recommend testing TPMT activity before starting these drugs.
Signs & symptoms
GARD doesn't list specific symptoms for this condition yet. Problems may appear with thiopurine drugs, as the summary describes:
- Anemia: pale skin, weakness, and tiredness
- Low white blood cells (neutropenia) and frequent infections
- Low platelets (thrombocytopenia) and easy bruising or bleeding
Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.
Diagnosis
- 1Talk with your doctor
Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.
- 2See a specialist
Your doctor may refer you to a specialist who knows rare conditions.
- 3Ask which tests can help
Your care team will decide which exams and tests can confirm the diagnosis.
Care & treatment
- Care team
- A doctor familiar with rare conditions, plus specialists as needed
- Expert care
- Ask about multidisciplinary care centers for rare conditions
- Treatment
- GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
- Research
- Clinical trials and observational studies may be options. See the research section below.
General information, not medical advice. Your care team makes the decisions.
Everyday life
Living with a rare condition is easier with support.
- Connect with rare disease patient organizations for support
- Keep notes on symptoms, changes and questions for appointments
- Ask about patient registries that help research
- Look into financial aid and travel resources for care visits
Quick facts
GARD says this condition is autosomal recessive, so a child inherits a changed copy of the gene from each parent. The record doesn't name the gene.
Also known as: inborn error of thiopurine s-methyltransferase activity; inborn thiopurine s-methyltransferase activity disorder; poor metabolism of thiopurines-1; rare inborn error of thiopurine s-methyltransferase activity; thiopurine s methyltranferase deficiency; thiopurines, poor metabolism of, 1
Patient organizations
Rare-disease groups that can help
- Global GenesRare Diseases · United States
- National Organization for Rare DisordersRare Diseases · United States
- Genetic AllianceRare Diseases · United States
- RARE FoundationRare Diseases · United States
You are more than your diagnosis
Perspectives from people navigating life with Thiopurine S-methyltransferase deficiency.
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