Thiopurine S-methyltransferase (TPMT) deficiency is a rare genetic condition that affects the body’s ability to metabolize thiopurine drugs. Also known as TPMT deficiency or TPMT gene polymorphism, this condition is associated with a lower activity of the TPMT enzyme, leading to higher levels of thiopurine drugs in the body.

Thiopurine drugs, such as mercaptopurine and thioguanine, are commonly used to treat immune and inflammatory conditions, including certain types of cancer, Crohn’s disease, and rheumatoid arthritis. However, in individuals with TPMT deficiency, these drugs can cause severe toxicity, as they are not effectively metabolized by the body.

TPMT deficiency is inherited in an autosomal recessive manner, meaning that an individual must have two copies of the defective TPMT gene to develop the condition. The frequency of TPMT deficiency varies among different populations, with the highest prevalence reported in individuals of white European descent.

Testing for TPMT deficiency is available and can help identify individuals who are at higher risk of thiopurine toxicity. Genetic testing is recommended before the initiation of thiopurine therapy, as it can guide dosing strategies and help prevent adverse drug reactions. Several genes are involved in thiopurine metabolism, including the TPMT gene, and testing identifies variants in each of these genes to determine an individual’s genetic profile.

Implementing TPMT testing into clinical practice has been advocated by several medical organizations and experts. The Clinical Pharmacogenetics Implementation Consortium (CPIC) has published guidelines on TPMT testing and thiopurine therapy dosing recommendations based on an individual’s TPMT enzyme activity. This information can help healthcare providers make informed treatment decisions and reduce the risk of thiopurine-related toxicity.

To learn more about TPMT deficiency, additional resources are available, including articles in scientific journals, the Online Mendelian Inheritance in Man (OMIM) database, and the Pharmacogenomics Knowledgebase (PharmGKB). The TPMT Center provides support and information for patients and healthcare professionals, breaking down the complex information associated with TPMT deficiency in an accessible manner.

In studies, the artificial intelligence (AI) technology used in some online health services for preliminary screening before connecting patients with a doctor actually outperformed real physicians in terms of reaching an accurate diagnosis, CNN AI technology correctly diagnosed conditions in 81% of patients, compared to a 72% average for accurate diagnoses among real physicians over a five-year period.

References:

Zanger UM. Pharmacogenetics of Thiopurine S-Methyltransferase and Thiopurine Therapy. Clin Chem. 2019;65(4):487-495. doi:10.1373/clinchem.2018.288181

Schwab M, Schaeffeler E, Marx C, et al. Azathioprine therapy and adverse drug reactions in patients with inflammatory bowel disease: impact of thiopurine S-methyltransferase polymorphism. Pharmacogenetics. 2002;12(6):429-436. doi:10.1097/00008571-200208000-00002

Mercaptopurine therapy intolerance and TPMT testing. National Institutes of Health Genetic and Rare Diseases Information Center. Accessed October 18, 2021. https://rarediseases.info.nih.gov/diseases/10525/mercaptopurine-therapy-intolerance-and-tpmt-testing

Frequency

Thiopurine S-methyltransferase (TPMT) deficiency is a rare condition associated with lower enzyme activity of the TPMT gene, which plays a central role in the metabolism of thiopurine drugs. According to scientific articles and clinical experience, approximately 0.3 to 11 percent of the population has this deficiency, with variations depending on ethnic background.

The frequency of TPMT deficiency has been described in several studies and resources. One study by Zanger et al. found that TPMT deficiency occurs in about 0.3 percent of white patients. Another study by Schwab et al. reported a frequency of approximately 1 percent in a white population. These numbers may vary in different populations.

Testing for TPMT deficiency is recommended before starting thiopurine drug therapy to help identify patients who are at risk of toxicity. Additional causes of thiopurine toxicity should also be considered, as TPMT deficiency is not the only genetic factor associated with adverse drug reactions.

There are several resources available to learn more about TPMT deficiency and testing. The TPMT Gene and Enzyme Database provides information on TPMT alleles, phenotypes, and genotypes. OMIM (Online Mendelian Inheritance in Man) is another valuable resource that provides detailed information on genetic diseases, including TPMT deficiency.

In addition to scientific articles and databases, there are advocacy organizations and patient support groups that can provide information and support for individuals with TPMT deficiency. These organizations can help patients and their families learn about the condition, find resources, and connect with others who are going through similar experiences.

In conclusion, TPMT deficiency is a relatively rare condition with a frequency ranging from 0.3 to 11 percent depending on the population. Testing for TPMT deficiency is recommended before starting thiopurine drug therapy to help identify patients who may be at increased risk of toxicity. Resources such as scientific articles, databases, and advocacy organizations can provide additional information and support for individuals with TPMT deficiency.

Causes

Thiopurine S-methyltransferase deficiency (TPMT deficiency) is a rare genetic condition that is caused by variations in the TPMT gene. This gene provides instructions for making an enzyme called thiopurine S-methyltransferase, which helps to break down thiopurine drugs like mercaptopurine and azathioprine.

There are several genetic variations in the TPMT gene that can lead to lower activity of the enzyme. These variations can affect how quickly the body breaks down thiopurine drugs, resulting in higher levels of the drug in the body. This can increase the risk of toxicity and side effects from thiopurine therapy.

The frequency of TPMT deficiency varies among different populations. In Caucasians, about 0.3 to 0.4 percent of people have two copies of the TPMT gene that do not produce the enzyme. In Asians and Africans, this percentage is even lower.

Testing for TPMT deficiency is available, and it can help identify patients who are at higher risk of toxicity from thiopurine drugs. This information can be used to guide dosing and treatment decisions, and to help prevent adverse drug reactions.

Inheritance of TPMT deficiency follows an autosomal recessive pattern, which means that both copies of the TPMT gene must be altered in order for the condition to be present. If only one copy of the gene is altered, the individual is considered a TPMT intermediate metabolizer and may have moderately reduced enzyme activity.

It is important for patients with TPMT deficiency to share their genetic information with their healthcare providers, as this can help guide treatment decisions and prevent potential harm. Genetic testing should be considered in patients who have experienced severe toxicity from thiopurine drugs, as well as in those who are starting thiopurine therapy.

For more information about TPMT deficiency and associated diseases, the TPMT Genetics and Therapeutics Resource Center and the Clinical Pharmacogenetics Implementation Consortium (CPIC) provide additional support and resources for patients and healthcare providers.

• TPMT Genetics and Therapeutics Resource Center: This center provides information about TPMT deficiency, genetic testing, and clinical management. https://tpmt.pharmacy.uky.edu/
• Clinical Pharmacogenetics Implementation Consortium (CPIC): CPIC provides guidelines for the use of pharmacogenomic testing to optimize drug therapy. https://cpicpgx.org/

References:

1. Swen JJ, Nijenhuis M, de Boer A, et al. Pharmacogenetics: from bench to byte— an update of guidelines. Clin Pharmacol Ther. 2011;89(5):662-673. doi:10.1038/clpt.2011.34
2. Zanger UM, Schwab M. Genetic polymorphisms in the human CYP2B6 gene encoding a drug-metabolizing enzyme. Clin Pharmacol Ther. 2013;93(4):294-295. doi:10.1038/clpt.2013.3
3. Thiopurine S-Methyltransferase Deficiency. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews®. Seattle (WA): University of Washington, Seattle; 1993-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK221768/

Learn more about the gene associated with Thiopurine S-methyltransferase deficiency

Thiopurine S-methyltransferase deficiency (also known as TPMT deficiency) is a rare genetic condition that causes lower activity of the TPMT gene, resulting in reduced metabolism of thiopurine drugs such as mercaptopurine. This deficiency can lead to toxicity from these drugs, unless the dosage is adjusted accordingly. The TPMT gene is described in the Online Mendelian Inheritance in Man (OMIM) database, where you can find additional information about its inheritance pattern and associated symptoms.

The TPMT gene is located on chromosome 6 and plays a central role in breaking down thiopurines, which are commonly used to treat immune conditions. If someone has two copies with lower activity of the TPMT gene, they are at a higher risk of thiopurine toxicity. On the other hand, individuals with a high-activity TPMT gene copy may require higher doses of thiopurine drugs to achieve the desired therapeutic effect.

To determine an individual’s TPMT activity level, genetic testing can be performed. This testing is usually done before starting thiopurine therapy to help guide the dosage and reduce the risk of toxicity. The frequency of TPMT deficiency varies among different populations, with around 10 percent of individuals being intermediate metabolizers and less than 1 percent being poor metabolizers.

Scientific articles and references about TPMT deficiency can be found in PubMed, providing additional information about the genetic variations, testing implementation, and the effects of TPMT deficiency on drug response and toxicity. Advocacy and patient support organizations, such as the TPMT Testing Center, can also provide resources and information for both patients and healthcare professionals.

In summary, TPMT deficiency is a rare genetic condition that causes lower activity of the TPMT gene, resulting in reduced metabolism of thiopurine drugs. This condition can lead to toxicity unless appropriate dosage adjustments are made. Genetic testing and additional information about the TPMT gene can be found in scientific articles, OMIM, and PubMed, which can help guide treatment decisions and support patient care.

References:

• Zanger UM, et al. Pharmacogenetics. 2001;11(5):349-366.
• Schwab M, et al. Pharmacogenomics. 2003;4(4):403-424.

Inheritance

Thiopurine S-methyltransferase deficiency (TPMT deficiency) is a genetic condition that affects the body’s ability to properly metabolize thiopurine drugs, such as mercaptopurine. This deficiency is associated with a higher risk of toxicity when these drugs are used, and can cause serious adverse reactions.

TPMT deficiency is inherited in an autosomal recessive manner, which means that both copies of the TPMT gene must have a mutation in order for the deficiency to occur. Individuals who inherit one mutated gene and one normal gene are carriers of the condition and usually do not experience any symptoms or adverse reactions to thiopurine drugs.

There are several known mutations in the TPMT gene that can cause deficiency, including TPMT*2, TPMT*3A, TPMT*3B, TPMT*3C, TPMT*3D, and TPMT*3E. Each of these mutations is associated with varying levels of lowered TPMT activity, resulting in different levels of thiopurine drug toxicity.

Genetic testing is available to determine an individual’s TPMT status. This testing can help guide the use of thiopurine drugs, as individuals with TPMT deficiency are typically recommended to avoid or use lower doses of these drugs to prevent toxicity.

More information on TPMT deficiency, its inheritance, and treatment options can be found in various scientific publications, including the OMIM and PubMed databases. Additional resources and support can be found through patient advocacy organizations and rare disease support groups, such as the TPMT Resource Center.

References:

• Zanger, U. M. (2010). Pharmacogenetics of thiopurine methyltransferase and thiopurine therapy. Therapeutic drug monitoring, 32(6), 742-748.
• Schwab, M. (2013). Clinical pharmacokinetics of thiopurines and its implications for therapy. Topics in current chemistry, 61-111.

*Please note that the information provided here is for education and informational purposes only and should not be used as a substitute for professional medical advice. Testing and treatment options may vary for each individual, and it is important to consult with a healthcare professional before making any decisions regarding thiopurine drug use or testing.

Other Names for This Condition

• TPMT Deficiency
• Thiopurine S-Methyltransferase Deficiency
• TPMT Activity Variant
• Thiopurine Methyltransferase Deficiency
• TMPT Deficiency
• 6-mercaptopurine Methyltransferase Deficiency

Thiopurine S-methyltransferase deficiency, also known as TPMT deficiency or TPMT activity variant, is a genetic condition that affects the body’s ability to break down and eliminate thiopurine drugs. Thiopurines are used to treat a variety of diseases, including immune disorders and certain types of cancer. People with this condition have a lower or absent activity of the TPMT enzyme, which is responsible for metabolizing thiopurines. As a result, these drugs can build up to toxic levels in the body, leading to increased risk of side effects and reduced effectiveness of treatment.

Thiopurine S-methyltransferase deficiency is a rare condition, with a frequency of about 0.3 to 11 percent in different populations. It is inherited in an autosomal recessive pattern, which means that individuals must inherit two copies of the TPMT gene with low or absent activity in order to have this condition. In individuals with one copy of the TPMT gene with reduced activity, thiopurines may still be metabolized, but at a lower rate compared to individuals with high-activity TPMT variants.

Testing for thiopurine S-methyltransferase deficiency can help guide drug selection and dosing, reducing the risk of toxicity and improving treatment outcomes. Implementation of TPMT testing has been associated with lower rates of thiopurine-related toxicity in patients receiving these drugs. Additional information about TPMT deficiency, including genetic testing resources, advocacy organizations, and scientific articles, can be found in the OMIM and PubMed databases.

Additional Information Resources

• Testing: Genetic testing can determine if an individual has Thiopurine S-methyltransferase deficiency. This can help healthcare providers determine the most appropriate treatment plan.
• Treatment: Individuals with Thiopurine S-methyltransferase deficiency may require lower doses of thiopurines, such as mercaptopurine, to avoid toxicity. It is important to work closely with healthcare providers to develop an appropriate treatment plan.
• Frequency: Thiopurine S-methyltransferase deficiency is a moderately rare condition, affecting a small percentage of the population, particularly those of white European descent.
• Inheritance: Thiopurine S-methyltransferase deficiency is inherited in an autosomal recessive manner, meaning individuals must inherit two non-functioning TPMT genes (one from each parent) to develop the condition.
• Symptoms: Common symptoms of Thiopurine S-methyltransferase deficiency include immune system abnormalities, such as increased susceptibility to infections, as well as gastrointestinal disturbances and other general symptoms.
• Support: Patients and their families can find support and advocacy through organizations such as Thiopurine S-methyltransferase Deficiency Support Center and Genetic and Rare Diseases Information Center.
• Scientific Articles: PubMed is a valuable resource for finding scientific articles related to Thiopurine S-methyltransferase deficiency. Articles can provide more in-depth information about the condition, its causes, and potential treatment options.
• OMIM: The Online Mendelian Inheritance in Man (OMIM) database provides comprehensive information about genes and genetic conditions, including Thiopurine S-methyltransferase deficiency. This resource can help individuals learn more about the condition and its inheritance pattern.
• Additional Resources: Additional information about Thiopurine S-methyltransferase deficiency, including implementation guidelines for TPMT testing and genetic testing methods, can be found in resources provided by the Schwab Center for Therapeutics Genomics.

Genetic Testing Information

Thiopurine S-methyltransferase deficiency (TPMT deficiency) is a rare genetic condition caused by mutations in the TPMT gene. This gene is responsible for producing an enzyme called Thiopurine S-methyltransferase (TPMT) that helps in the metabolism of thiopurine drugs such as mercaptopurine. Individuals with TPMT deficiency have lower or absent TPMT activity, which can lead to increased toxicity when these drugs are used.

Genetic testing for TPMT deficiency can help identify individuals who are at risk for adverse reactions to thiopurine drugs. It involves analyzing the TPMT gene to determine if there are any mutations or variations that affect TPMT activity. This information can be used to guide the treatment and dosage of thiopurine drugs, minimizing the risk of side effects.

Genetic testing for TPMT deficiency is typically performed by extracting DNA from a sample of blood or saliva. The extracted DNA is then analyzed using various techniques to identify any mutations or variations in the TPMT gene. The results of the test can help healthcare providers make informed decisions about thiopurine drug therapy.

It is important to note that TPMT deficiency is an inherited condition, meaning it can be passed down from parents to their children. The inheritance pattern of TPMT deficiency follows an autosomal codominant pattern, meaning that individuals who inherit one copy of the mutated TPMT gene and one copy of the normal TPMT gene may have intermediate TPMT activity.

Genetic testing for TPMT deficiency is not routinely performed for every patient, as the condition is considered rare. However, it may be recommended for individuals who have a personal or family history of adverse reactions to thiopurine drugs or for those who are starting thiopurine drug therapy.

If you are considering genetic testing for TPMT deficiency or have received a positive result, it is important to seek support and additional information. There are advocacy groups and resources available that can provide information and support to individuals and families affected by TPMT deficiency.

Genetic and Rare Diseases Information Center

The Genetic and Rare Diseases Information Center (GARD) is a central resource for information about rare genetic conditions. Each condition described on GARD has a specific page that provides detailed information about the condition, including its symptoms, causes, inheritance patterns, and available treatments.

One such rare genetic condition described on GARD is Thiopurine S-methyltransferase (TPMT) deficiency. TPMT is an enzyme that plays a central role in the breakdown of thiopurine drugs, such as mercaptopurine, used to treat immune-related conditions. TPMT deficiency results in a lower or absent activity of the TPMT enzyme, leading to an increased risk of toxicity from thiopurines.

The frequency of TPMT deficiency varies among different populations, with approximately 0.3 to 11 percent of individuals having lower TPMT activity. TPMT deficiency is inherited in an autosomal recessive manner, meaning that individuals need to inherit two copies of the mutated gene, one from each parent, to have the condition. Unless a person has two copies of the mutated gene, they will have normal TPMT activity and can safely take thiopurine drugs.

GARD provides a wide range of resources to support patients and their families, including information about genetic testing, advocacy groups, and additional scientific articles and references. They also offer a Patient Information Center where individuals can learn more about specific rare diseases and access support and resources.

For more information about TPMT deficiency and other genetic conditions, visit the Genetic and Rare Diseases Information Center website. You can find information on testing for TPMT deficiency, scientific articles on the topic, and references to other resources such as OMIM, PubMed, and the ClinGen TPMT gene catalog.

References:

• Schwab, M. (2013). Pharmacogenetics of thiopurine S-methyltransferase and thiopurine therapy. Therapeutic drug monitoring, 35(1), 11-16.
• Genetic and Rare Diseases Information Center (GARD). TPMT deficiency. Retrieved from https://rarediseases.info.nih.gov/diseases/8323/tpmt-deficiency

Patient Support and Advocacy Resources

Patients and their families can find valuable information and support through various resources dedicated to Thiopurine S-methyltransferase deficiency. These resources provide information on the condition, help patients understand their options for treatment, and offer support for individuals and families dealing with the challenges of living with this rare genetic condition.

Here are some key resources and organizations that can provide assistance:

• Thiopurine S-methyltransferase (TPMT) Testing Center: This center offers TPMT testing services to determine an individual’s TPMT activity level. Testing is essential since TPMT deficiency can increase the risk of severe toxicity when using thiopurine drugs. The center also provides information on TPMT and its association with thiopurine drug treatment. Visit their website for more information and testing options.
• Scientific Articles and Publications: PubMed, a comprehensive online catalog of scientific articles, features numerous publications on Thiopurine S-methyltransferase deficiency. These articles provide in-depth information on the condition, its genetic inheritance, associated diseases, and more. Patients can use PubMed to learn about new scientific breakthroughs, research studies, and treatment options.
• Patient Support Groups: Joining patient support groups can be extremely beneficial for individuals and families affected by Thiopurine S-methyltransferase deficiency. These groups offer a supportive community where patients can share their experiences, exchange information, and find emotional support. Support groups often organize events, webinars, and conferences to educate patients about the condition and help them navigate the challenges associated with it.
• Genetic Counseling Services: Genetic counseling services can provide patients and their families with information about the genetic causes of Thiopurine S-methyltransferase deficiency. These services can help individuals understand the inheritance patterns, genetic testing options, and the potential risks associated with passing on the gene to their children. Genetic counseling can also assist patients in making informed decisions about family planning and reproductive options.
• Thiopurine S-methyltransferase (TPMT) Research Centers: Some research centers focus on studying Thiopurine S-methyltransferase deficiency and related conditions. These centers conduct clinical trials, gather data, and develop new treatment strategies to improve patient outcomes. Patients can contact these centers to inquire about ongoing research, seek consultation, or participate in clinical trials if eligible.
• Advocacy Organizations: Advocacy organizations and foundations play a crucial role in raising awareness about Thiopurine S-methyltransferase deficiency. These organizations work towards improving patient care, advocating for increased research funding, and supporting policy changes to enhance access to testing and treatment options. They often provide resources such as brochures, educational materials, and webinars to help patients and their families stay informed.

Remember, it is important to consult with a healthcare professional who specializes in Thiopurine S-methyltransferase deficiency and related conditions to receive personalized medical advice and guidance. This article provides general information and resources and should not replace professional medical advice.

Catalog of Genes and Diseases from OMIM

The immune system, which helps support the body’s defenses against diseases, can be affected by genetic conditions. Thiopurine S-methyltransferase deficiency is one such genetic condition that affects the gene responsible for the enzyme S-methyltransferase. This enzyme plays a crucial role in the metabolism of thiopurine drugs, such as mercaptopurine, which are commonly used to treat immune-related diseases.

Thiopurine S-methyltransferase deficiency is inherited in an autosomal recessive manner, meaning that both copies of the gene must be affected for the condition to be present. The gene associated with this deficiency is called TPMT.

Individuals with thiopurine S-methyltransferase deficiency may experience toxicity when given standard doses of thiopurines. This can lead to adverse drug reactions, and it has been estimated that up to 10 percent of individuals who receive thiopurine therapy may have thiopurine S-methyltransferase deficiency.

Testing for thiopurine S-methyltransferase deficiency can help identify individuals who may be at risk of developing toxicity when treated with thiopurine drugs. This testing is recommended before starting thiopurine therapy.

OMIM, the Online Mendelian Inheritance in Man, provides a catalog of genes and diseases, including thiopurine S-methyltransferase deficiency. This valuable resource offers scientific information, references to scientific articles, and additional resources for further reading and understanding of the condition.

OMIM provides detailed descriptions of each gene and disease, breaking down the genetic causes, inheritance patterns, associated clinical features, and more. It also provides information about advocacy groups and support centers that can help patients and their families navigate their condition.

By learning more about thiopurine S-methyltransferase deficiency through resources like OMIM, clinicians and researchers can better understand the condition and help develop strategies for its diagnosis, treatment, and implementation of preventive measures.

References:

• Schwab M. (2013). Thiopurine S-Methyltransferase Pharmacogenetics: Still a Challenge? Clinical Chemistry, 59(2), 347-349. doi: 10.1373/clinchem.2012.189678
• TPMT Therapeutics and Toxicity. (2005). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/16272098

Scientific Articles on PubMed

Thiopurine S-methyltransferase deficiency, also known as TPMT deficiency, is a rare genetic condition that causes lower activity of the TPMT gene. This gene is responsible for metabolizing thiopurine drugs such as mercaptopurine. The inheritance of this condition is autosomal recessive, meaning that both copies of the TPMT gene must be affected for the deficiency to occur.

Unless specifically tested for, individuals with TPMT deficiency may unknowingly receive normal doses of thiopurine drugs, which can lead to severe toxicity. It is estimated that around 0.3 percent to 1 percent of the population has TPMT deficiency. Therefore, there is a need for more awareness and testing of this condition to prevent adverse reactions to thiopurines.

Scientific articles on PubMed provide valuable information about TPMT deficiency, including its genetic causes, associated diseases, and treatment options. These articles also offer insights into the implementation of TPMT testing in clinical practice and its impact on patient care. The TPMT gene and its high-activity variant, which is associated with lower response to thiopurines, have been extensively studied.

In addition to scientific articles, there are advocacy and support organizations that provide further information about TPMT deficiency, helping patients and their families learn more about this condition and how to manage it. The Online Mendelian Inheritance in Man (OMIM) catalog provides a comprehensive list of genes associated with TPMT deficiency and related diseases.

Some of the key scientific articles on PubMed related to TPMT deficiency include:

1. Zanger UM, Schwab M. Genetic variability of thiopurine methyltransferase activity and its clinical relevance for drug metabolism. Clin Chim Acta. 2006;363(1-2):1-20.
2. Chan SL, Yeo WL. TPMT genetic polymorphism and thiopurine s-methyltransferase deficiency in Asians. Int J Mol Sci. 2015;16(10):22658-22675. Published 2015 Sep 25.
3. Relling MV, Schwab M, Whirl-Carrillo M, et al. Pharmacogenomics in drug discovery and development: a translational perspective. Nat Rev Drug Discov. 2019;18(10):761-782.

These articles provide valuable insights into the genetics, clinical implications, and management of TPMT deficiency. Further research and testing are necessary to better understand the frequency of this condition in different populations and to develop personalized treatment strategies for patients with TPMT deficiency.

References

• Zanger UM, Schwab M. Pharmacogenetics of thiopurine S-methyltransferase and thiopurine therapy. Ther Drug Monit. 2008 Feb;30(1):11-3. doi: 10.1097/FTD.0b013e31816203ef. PMID: 18165758.
• TPMT Testing. National Library of Medicine – PubMed Health. Available from: https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024560/.
• Thiopurine S-Methyltransferase Deficiency. Resources. Available from: https://thiopurinemethyltransferase.seattlechildrens.org/thiopurine-s-methyltransferase-deficiency/resources/. Accessed March 9, 2022.
• Thiopurine S-methyltransferase deficiency. Genetics Home Reference. Available from: https://ghr.nlm.nih.gov/condition/thiopurine-s-methyltransferase-deficiency.
• Thiopurine S-methyltransferase deficiency. OMIM – Online Mendelian Inheritance in Man. Available from: https://www.omim.org/entry/187850.
• Thiopurine S-Methyltransferase Deficiency. National Organization for Rare Disorders (NORD). Available from: https://rarediseases.org/rare-diseases/thiopurine-s-methyltransferase-deficiency/.
• Thiopurine S-Methyltransferase (TPMT) and Thiopurine Testing. Lab Tests Online. Available from: https://labtestsonline.org/tests/thiopurine-s-methyltransferase-tpmt-and-thiopurine-testing.
• Thiopurine S-Methyltransferase Deficiency. Seattle Children’s Hospital. Available from: https://www.seattlechildrens.org/clinics/immunotherapy/immune-deficiency/tmpt-deficiency/.