TPMT is a cytosolic enzyme that catalyzes the S-methylation of aromatic and heterocyclic sulfhydryl compounds, including medications such as mercaptopurine and thioguanine. TPMT activity exhibits autosomal codominant genetic polymorphism, and patients inheriting TPMT deficiency are at high risk of potentially fatal hematopoietic toxicity. The most prevalent mutant alleles associated with TPMT d...

The activity of the enzyme thiopurine methyltransferase (TPMT) is regulated by a common genetic polymorphism. One in 300 individuals lack enzyme activity and 11% are heterozygous for a variant low activity allele and have an intermediate activity. The thiopurine drugs azathioprine, mercaptopurine and thioguanine are substrates for TPMT; these drugs exhibit well documented myelosuppressive effec...

methylation in azathioprine (AZA), thioguanine and 6-mercaptopurine (6-MP). The low TPMT activity in erythrocytes has been associated with an increased risk of severe and potentially fatal hematopoietic toxicity caused by the accumulation of the cytotoxic metabolites of thiopurine drugs. Genetic polymorphism of the TPMT activity in human was first reported by Weinshilboum and Sladek. Four varia...

BACKGROUND Interindividual differences in therapeutic efficacy in patients treated with thiopurines might be explained by the presence of thiopurine S-methyltransferase (TPMT) alleles that encode for reduced TPMT enzymatic activity. It is therefore of value to know an individual's inherent capacity to express TPMT. METHOD We developed a pyrosequencing method to detect 10 single-nucleotide pol...

OBJECTIVE Thiopurine S-methyltransferase (TPMT) is a cytosolic enzyme that preferentially catalyzes the S-methylation of aromatic and heterocyclic sulfhydryl compounds, including Azathioprine (AZA). It has been reported that the level of AZA toxicity is dependent on the TPMT genotypes in Caucasian individuals; we thus investigated this relationship in Japanese. METHODS The TPMT genotype was d...

I. Aetna considers TPMT gene mutation or TPMT phenotypic assays (e.g., Prometheus TPMT Genetics, Prometheus TPMT Enzyme) medically necessary prior to initiation of 6mercaptopurine or azathioprine therapy. Only 1 genotypic or phenotypic assay of TPMT activity is necessary per member per lifetime. TPMT gene mutation assays and TPMT phenotypic assays are considered experimental and investigational...

Thiopurine methyltransferase (Tpmt) is the primary enzyme responsible for deactivating thiopurine drugs. Thiopurine drugs (i.e., thioguanine [TG], mercaptopurine, azathioprine) are commonly used for the treatment of cancer, organ transplant, and autoimmune disorders. Chronic thiopurine therapy has been linked to the development of brain cancer (most commonly astrocytomas), and Tpmt status has b...

Thiopurine methyltransferase (TPMT) is an important enzyme in the metabolism of 6-mercaptopurine (6MP), which is used in the treatment of acute lymphoblastic leukemia (ALL). TPMT catalyzes the formation of methylthioinosine monophosphate (MetIMP), which is cytotoxic for cultured cell lines, and it plays a role in detoxification of 6MP. Population studies show a genetic polymorphism for TPMT wit...

The influence of thiopurine methyltransferase (TPMT) genotype on treatment outcome was investigated in the United Kingdom childhood acute lymphoblastic leukaemia trial ALL2003, a trial in which treatment intensity was adjusted based on minimal residual disease (MRD). TPMT genotype was measured in 2387 patients (76% of trial entrants): 2190 were homozygous wild-type, 189 were heterozygous for lo...

The molecular basis for the genetic polymorphism of thiopurine S -methyltransferase (TPMT) has been estab-lished for Caucasians, but it remains to be elucidated in African populations. In the current study, we determined TPMT genotypes in a population of 248 African-Americans and compared it with allele frequencies in 282 Caucasian Americans. TPMT genotype was determined in all individuals with...