scholarly journals TPMT Gene

2020 ◽  
Author(s):  
Keyword(s):  
Tpmt Gene

scholarly journals High-Throughput Genotyping of Thiopurine S-Methyltransferase by Denaturing HPLC

2001 ◽  
Vol 47 (3) ◽  
pp. 548-555 ◽  
Author(s):  
Elke Schaeffeler ◽  
Thomas Lang ◽  
Ulrich M Zanger ◽  
Michel Eichelbaum ◽  
Matthias Schwab
Keyword(s):  
High Throughput ◽  
Direct Sequencing ◽  
False Negative ◽  
Rapid Screening ◽  
Tpmt Activity ◽  
Polymorphism Analysis ◽  
Specific Pcr ◽  
Restriction Fragment Polymorphism ◽  
Allele Specific ◽  
Tpmt Gene

Abstract Background: The thiopurine S-methyltransferase (TPMT) genetic polymorphism has a significant clinical impact on the toxicity of thiopurine drugs, which are used in the treatment of leukemia and as immunosuppressants. To date, 10 mutant alleles are known that are associated with intermediate or low TPMT activity. To facilitate rapid screening of clinically relevant TPMT mutations, we developed a strategy of high-throughput genotyping by applying denaturing HPLC (DHPLC). Methods: To test the specificity and efficiency of the DHPLC method, 98 DNA samples from a selected population of patients receiving thiopurine therapy or with previous thiopurine withdrawal were analyzed for the most frequent mutant TPMT alleles, *2 and *3A, which contain key mutations in exons 5, 7, and 10 to identify clearly different elution profiles. All fragments were examined by direct sequencing. Additionally, to test the sensitivity of DHPLC analysis, genotyping for the *2 and *3A alleles of all 98 DNA samples was performed by PCR-based methods (PCR-restriction fragment polymorphism analysis and allele-specific PCR). Results: The presence of mutations discriminating for alleles *2, *3A, *3C, and *3D, as well as various silent and intron mutations, were correctly predicted by DHPLC in 100% of the samples as confirmed by direct sequencing. Comparison with PCR-based methods for alleles *2 and *3 produced an agreement of 100% with no false-negative signals. Conclusions: DHPLC offers a highly sensitive, rapid, and efficient method for genotyping of the relevant TPMT mutations, discriminating at least for alleles *2 and *3, in clinical and laboratory practice. Additionally, DHPLC allows a simultaneous screening for novel genetic variability in the TPMT gene.

scholarly journals Importance of genotyping of Thiopurine S-methyltransferase in children with acute lymphoblastic leukaemia during maintenance therapy

2008 ◽  
Vol 136 (11-12) ◽  
pp. 609-616 ◽  
Author(s):  
Lidija Dokmanovic ◽  
Dragana Janic ◽  
Nada Krstovski ◽  
Branka Zukic ◽  
Natasa Tosic ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukaemia ◽  
Lymphoblastic Leukaemia ◽  
Tandem Repeats ◽  
Gene Mutations ◽  
Maintenance Phase ◽  
Variable Number ◽  
Childhood All ◽  
Dose Therapy ◽  
Significant Difference ◽  
Tpmt Gene

INTRODUCTION Thiopurine S-methyltransferase (TPMT) is an enzyme that catalyses the inactivation of mercaptopurine (MP) which is widely used in the treatment of acute lymphoblastic leukaemia (ALL) of childhood. Potentially fatal myelotoxicity may develop after standard doses of MP in TPMT deficient patients. OBJECTIVES To establish if individually tailored doses of MP can reduce myelotoxicity in ALL patients carrying mutations in the TPMT gene. To establish if variable number of tandem repeats (VNTR) genotype influences the treatment effects of MP. METHOD Fifty randomly selected patients treated according to ALL IC-BFM 2002 protocol were tested for most frequent TPMT gene mutations using PCR based methods. VNTR genotype was determined in 20 children by PCR methods. During the maintenance phase, we recorded the number of weeks when therapy was applied in either full doses, reduced doses or when patients were without any therapy. RESULTS Fifty children were examined, 29 boys (58%) and 21 girls (42%); age ranged from 1.8-17.3 years (median 6.2 years). Four patients (8%) were heterozygous for TPMT mutations, all of them carrying the TPMT*3A variant. After 12, 14, 16 and 19 weeks of therapy with reduced doses of MP, the patients switched to full doses due to good tolerance. There was no therapy omission. Cumulative dose of MP was reduced for 7.8%, 7.4%, 11.2% and 16.6%, respectively, in patients with TPMT mutations. No significant difference was found between children with no mutations and TPMT heterozygotes regarding full dose therapy (53.6 vs. 55.7 weeks, respectively) and reduced dose therapy (19.9 vs. 15.2 weeks respectively). The number of detected VNTRs ranged from four to seven. The majority of patients had different number of VNTRs on homologous chromosomes. Most frequently detected polymorphism was VNTR*5. No correlation was found between TPMT and VNTR genotype inheritance. CONCLUSION Obeying pharmacogenetic principles in the treatment of childhood ALL may improve the tolerance of therapy with MP.

scholarly journals Association between the TPMT*3C (rs1142345) Polymorphism and the Risk of Death in the Treatment of Acute Lymphoblastic Leukemia in Children from the Brazilian Amazon Region

Genes ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1132
Author(s):  
Darlen Cardoso de Carvalho ◽  
Luciana Pereira Colares Leitão ◽  
Fernando Augusto Rodrigues Mello Junior ◽  
Alayde Vieira Wanderley ◽  
Tatiane Piedade de Souza ◽  
...  
Keyword(s):  
Native American ◽  
Acute Lymphoblastic Leukemia ◽  
High Risk ◽  
Lymphoblastic Leukemia ◽  
Brazilian Amazon ◽  
Childhood All ◽  
Risk Of Death ◽  
Native American Ancestry ◽  
High Contribution ◽  
Tpmt Gene

Acute lymphoblastic leukemia (ALL) is the leading cause of death from pediatric cancer worldwide. However, marked ethnic disparities are found in the treatment of childhood ALL with less effective results and higher mortality rates being obtained in populations with a high level of Native American ancestry. Genetic variations of the patient can affect resistance to ALL chemotherapy and potentially play an important role in this disparity. In the present study, we investigated the association of 16 genetic polymorphisms with the cell and metabolic pathways of the chemotherapeutic agents used in the treatment of ALL with the risk of death in treating childhood ALL in patients with a high contribution of Amerindian ancestry, coming from the Brazilian Amazon. The study included 121 patients with B-cell ALL treated with the BFM-2002 protocol. We are the first to identify the association between the TPMT gene rs1142345 polymorphism and the high risk of death in treating childhood ALL. Patients with the CC genotype had an approximately 25.5 times higher risk of dying during treatment of the disease than patients with other genotypes (p = 0.019). These results may help elucidate how the patient’s genetic characteristics contribute to the mortality disparity in populations with a high contribution of Native American ancestry. The rs1142345 variant of the TPMT gene could be used as a potential marker to early stratify patients at high risk of death in treating childhood ALL in the investigated population.

The Examination of a TPMT Gene Before Administration of Azathioprine in Rheumatology Practice and Identification of a Novel Variant p.W29R

2021 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Katerina Pavelcova ◽  
Petra Hanova ◽  
Hana Ciferska ◽  
Lenka Hasikova ◽  
Blanka Stiburkova
Keyword(s):  
Novel Variant ◽  
Tpmt Gene ◽  
Rheumatology Practice

scholarly journals Toxicity of azathioprine: why and when? analysis of the prevalence of polymorphism in Joinville, SC, Brazil

2012 ◽  
Vol 49 (2) ◽  
pp. 130-134 ◽  
Author(s):  
Gabriela Roncone Gastal ◽  
Simone Moreira ◽  
Caroline Furtado Noble ◽  
Leslie Ecker Ferreira ◽  
Paulo Henrique Condeixa de França ◽  
...  
Keyword(s):  
Blood Donors ◽  
Thiopurine Methyltransferase ◽  
Normal Allele ◽  
Wild Type ◽  
Drug Induced ◽  
Acute Leukemias ◽  
Allelic Variants ◽  
Risk Of Death ◽  
Inflammatory Bowel ◽  
Tpmt Gene

CONTEXT: The use of thiopurine drugs such as azathioprine and 6-mercaptopurine has become quite common in the treatment of inflammatory bowel disease, transplantation and acute leukemias. Despite their effectiveness, these drugs are capable of causing drug-induced toxicity with the risk of death by myelosuppression. It is now known that these complications occur because of genetic polymorphisms of the thiopurinemethyltransferase (TPMT) enzyme, responsible for its metabolism. OBJECTIVE: To assess the prevalence of thiopurine methyltransferase polymorphisms in the population of Joinville, SC, Brazil. METHODS: We analyzed the frequency of four main allelic variants of the TPMT gene in 199 blood donors from Joinville, from February to April 2010. RESULTS: The normal allele ("wild-type") was found in 93.9% of subjects studied. TPMT variants were detected in 12 subjects (6.03%). CONCLUSIONS: From this study, it was estimated at 6% the risk of toxicity by the administration of azathioprine and 6-mercaptopurine to patients in Joinville.

Genetic Polymorphism of Thiopurine S-Methyltransferase in the Russian Population.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4412-4412
Author(s):  
Elena V. Samochatova ◽  
Natalia V. Chupova ◽  
Anastasia E. Roudneva ◽  
Alexander G. Roumyantsev ◽  
Tatyana V. Nasedkina ◽  
...  
Keyword(s):  
Russian Federation ◽  
Hematologic Malignancies ◽  
The United States ◽  
Genotype 1 ◽  
The North ◽  
Non Hodgkin Lymphoma ◽  
Key Enzyme ◽  
The Russian Federation ◽  
Hematopoietic Toxicity ◽  
Tpmt Gene

Abstract Thiopurine S-methyltransferase (TPMT) is a key enzyme in the catabolism of 6-mercaptopurine (6MP), a key component of therapy for childhood acute lymphoblastic and promyelocytic leukemias and lymphoblastic non-Hodgkin lymphoma. TPMT mutations reduce TPMT enzymatic activity; therefore, TPMT-deficient patients develop severe hematopoietic toxicity when treated with standard doses of 6MP (50–75 mg/m2/day). The frequency of TPMT alleles has not previously been evaluated in the Russian Federation. We determined the allele frequency and the pattern of mutant TPMT alleles in Russian children with hematologic malignancies (leukemia/lymphoma) and other diseases, and in healthy adults, in different areas of the Russian Federation. A microchip was designed to detect the main mutant alleles of human TPMT (TPMT*2, *3A, *3B, *3D, *7, and *8) and was used to assay 982 samples. Only 3 inactivating mutations of the TPMT gene were identified: 45 subjects (4.6%) had TPMT genotype *1/*3A, 8 (0.8%) had *1/*3C, and 2 (0.2%) had *1/*2. No homozygous genotypes and no mutant *3B, *3D, *7, or *8 alleles were found. The estimated frequency of the wild-type allele was 97.1% (95% CI, 93.8%–100%) and that of variant alleles was 2.9% (95% CI, 0%–6%). Most individuals with the *1/*3A genotype were of Slavic background, and genotype *1/*3C was found in a buryat (Mongolian race) and in residents of the North Caucasian and the Urals regions. These findings indicate ethnic differences in the frequency of nonfunctional TPMT alleles. The overall frequency of mutant TPMT genotypes in the Russian Federation is 5.6%, which is similar to that observed in the white populations of the United States and Europe.

Inosine-Triphosphate-Pyrophosphatase Genotype Is a Determinant of Severe Fever with Neutropenia Following Treatment of Acute Lymphoblastic Leukemia with Combination Chemotherapy That Includes Mercaptopurine Adjusted for Thiopurine-S-Methyltransferase Genotype.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2827-2827
Author(s):  
Gabriele Stocco ◽  
Meyling Cheok ◽  
Wenjian Yang ◽  
Thierry Dervieux ◽  
Kristine Crews ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Acute Lymphoblastic Leukemia ◽  
Adverse Events ◽  
Lymphoblastic Leukemia ◽  
Variant Allele ◽  
Inosine Triphosphate Pyrophosphatase ◽  
Life Threatening ◽  
Variant Alleles ◽  
Grade 3 ◽  
Tpmt Gene

Abstract Germline polymorphisms can be significant determinants of toxicity to anti-leukemic therapy. For mercaptopurine (6MP) it is established that variant alleles of the thiopurine-S-methyl-transferase (TPMT) gene, resulting in low enzymatic activity, are associated with an increase in the concentration of thioguanine-nucleotide metabolites (TGN) and in the risk of hematotoxicity. Polymorphisms of genes encoding other enzymes involved in 6MP metabolism could also influence its pharmacokinetics and consequently its efficacy and toxicity. Among possible candidate genes, inosine-triphosphate-pyrophosphatase (ITPA) has been related to adverse events to thiopurine treatment of inflammatory bowel disease, but it has not been fully investigated for leukemia therapy. The aim of this study was to assess the association between severe life-threatening toxicities (Grade 3–4) during the continuation treatment of acute lymphoblastic leukemia (ALL) and the variant alleles of TPMT and ITPA genes, and the influence of these variant alleles on the concentration of 6MP metabolites, TGN and methylated nucleotides (MMPN). Patients with ALL on the St. Jude Total 13B protocol were assessed for toxicity according to NCI criteria. Relevant variant alleles of TPMT (SNPs rs1142345, rs1800462, rs1800660) and ITPA (SNP rs41320251) were determined using PCR assays. The association between the variant alleles and the development of adverse events during the continuation phase of treatment was assessed using weighted logistic regression. Concentrations of the two main metabolites of 6MP were measured in erythrocytes by HPLC; the association between genotypes and the concentrations of 6MP metabolites was evaluated using mixed linear effects models. TPMT and ITPA genotypes were determined for 233 patients; 13 (5.2%) were heterozygous for variant alleles of the TPMT gene and 31 (13.3%) for the ITPA gene; no patient had two variant alleles of either gene and 1 patient (0.4%) had a variant allele for both TPMT and ITPA. Since 6MP dose was individualized based on the TPMT variant allele among patients treated in the protocol, genetic polymorphisms of TPMT, not surprisingly, were not associated with toxicity. On the other hand, the presence of an ITPA variant allele was significantly associated with the incidence of Grade 3–4 fever with neutropenia in the univariate and in the multiple weighted logistic regression (odds ratio 3.0, 95% C.I. 1.2–7.8, p = 0.021). 6MP metabolites were measured in 257 samples from 108 patients, and the results revealed that variant alleles of both candidate genes were associated with changes in the concentration of the MMPN metabolites: TPMT with a reduction (p = 0.048) and ITPA with an increase (p = 0.047). Genetic polymorphism of ITPA rs41230251 is a significant determinant of severe and life-threatening fever with neutropenia and of 6MP metabolism in patients with ALL who are treated with 6MP doses individualized based on TPMT genotype.

Polymorphisms of the thiopurine S-methyl transferase gene (TMPT) in a Mexican population

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 20049-20049
Author(s):  
M. Candelaria ◽  
L. Taja-Chayeb ◽  
S. Vidal ◽  
O. Gutiérrez ◽  
P. Ostrosky ◽  
...  
Keyword(s):  
High Performance ◽  
Gene Mutations ◽  
Pcr Amplification ◽  
Mexican Population ◽  
Methyl Transferase ◽  
Other World ◽  
Peripheral Leukocytes ◽  
Analysis System ◽  
Tpmt Gene ◽  
Exon 10

20049 Background: Polymorphisms at the thiopurine S-methyltransferase coding gene (TPMT) determine enzyme activity and as a consequence the development of toxicity of thiopurine drugs. Methods: To test the frequency of polymorphisms of TPMT gene in Mexican population. 36 DNA samples from volunteer donors were analyzed. Genomic DNA from peripheral leukocytes was isolated by standard methods. Known (wild type and polymorphic) sequenced PCR fragments of the TPMT gene were used used as controls. PCR amplification: Fragments of the TPMT gene were amplified using the following oligonucleotides primers: Exon 5: 5′-CTGCATGTTCTTTGAAACCCTATGAA-3′ and 5′-CTTGAGGACAGAGAGGCTTTGACCTC-3′; exon 7: 5′-CTCCACACCCAGGTCC-ACACATT-3′ and 5′-GTATAGTACTAAAAAATTAAGACAGCTAAAC-3′; exon 10: 5′-AATCCTGATGTCATTCTTCATAGTATTT-3′ and 5′-CATCCATTACATTTTCAGG-CTTTAGCATAAT-3′. PCR products were then analyzed by denaturating high performance liquid chromatography (DHPLC) for the most frequent mutant TPMT alleles, according to the method developed by Schaeffeler et al (Clin Chem 2001; 47: 548) on an analysis system from Transgenomics Results: A high frequency of gene polymorphisms was identified, particularly in the exon 7 (14/36 = 38%), followed by exon 10 (3/36 = 8.3%) and 5 (2/36 = 5.5%). After analysing the three exons, the presence of mutations discriminating for TPMT alleles showed that 7/36 (19.4 %) were silent and located at T474C, in exon 7 (*1S) and 7/36 (19.4 %) were functional, and located in TPMT alleles *2 (2/36 = 5.5%), *3B (2/36 = 5.5%), *4 (2/36 = 5.5%) and *3B/4 (1/36= 2.7%). Conclusions: This is the first analysis of the polymorphisms at this gene in a Mexican population. The frequency of known silent polymorphisms was higher than those reported in other world regions but the frequency of functional polymorphism is within the range found in other reports. DHPLC is a highly sensitive, rapid and efficient method to identify relevant TPMT gene mutations which allows the screening for genetic variability in the TPMT gene . This trial was supported by a grant of CONACYT. No significant financial relationships to disclose.

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