Allelic variants of the thiopurine methyltransferase (TPMT) gene in
the Colombian population

Isaza, Carlos; Henao, Julieta; Am, López; Cacabelos, Ramón

doi:10.1358/mf.2003.25.6.769646

Cited by 32 publications

(18 citation statements)

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“…Accordingly, *3C allele frequency in Turkish population (0.9%) was significantly lower than the Africans (5.4-7.6%) but it was similar to other Caucasians (0.2-1.0%) and Asians (0.6-0.8%) [4,[19][20][21][22][23][24]28,29]. In the case of *3A defective allele, the frequency in Turkish population (0.9%) was lower than the American Caucasians (3.2%) and Latin American populations (3.1-3.6%) [19,25,26]. However, these differences were not statistically significant.…”

Section: Resultsmentioning

confidence: 59%

“…TPMT*3C is also seen in Caucasian population with allele frequency of 0.2-1.0% [19][20][21]. TPMT*2 is one of the three common mutant alleles which are generally confined to Caucasians and Latin American populations, with allele frequency of 0.2-0.7% [19,20,25,26]. Besides the interethnic variability, studies indicated that populations within the same ethnic origin can demonstrate significant differences in the distribution of common defective alleles [27].…”

Section: Introductionmentioning

confidence: 99%

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The low frequency of defective TPMT alleles in Turkish population: A study on pediatric patients with acute lymphoblastic leukemia

et al. 2007

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6-Mercaptopurine (6MP) is an essential anticancer drug used in the treatment of childhood acute lymphoblastic leukemia (ALL). Thiopurine methyltransferase (TPMT) polymorphisms are the major determinants of interindividual differences in the severe toxicity or efficacy of 6MP. Four variant alleles, TPMT*2, TPMT*3A, TPMT*3B, and TPMT*3C, are responsible over the 80% of low or undetectable enzyme activity. The frequencies of these variants were investigated among 106 children with ALL in Turkish population. TPMT*3A and TPMT*3C were the only deficiency alleles detected in Turkish population with an allele frequency of 0.9% for both. While *3C allele frequency in Turkish population was found to be very similar to Asian and other Caucasian populations, *3A allele frequency was significantly (P < 0.05) lower. So far, studies showed that the genetic polymorphisms of other drug metabolizing enzymes like CYP2E1, CYP1A1, GSTM1/ T1 in Turkish population were similar to Caucasian populations. However, we found that the distribution of TPMT polymorphisms in Turkish population was significantly lower than those in other Caucasians like British, French, and Italian whereas the distributions of TPMT variants were found to be very similar to Kazak population which is also Caucasian in ethnic origin. In this study, the clinical histories of the patients in the sample population were also examined, retrospectively. The patients with heterozygous or homozygous mutant genotypes had developed severe neutropenia and infection during 6MP therapy. The study provides the first data on the frequency of common TPMT variants in the Turkish population, based on analysis of pediatric patients with ALL.

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Section: Resultsmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

The low frequency of defective TPMT alleles in Turkish population: A study on pediatric patients with acute lymphoblastic leukemia

et al. 2007

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“…The most common allelic variant among Slovak IBD patients was TPMT*3A (3.2 %), while TPMT*2 and TPMT*3C were present only rarely (0.2 %). In Chinese, Japanese, Indian (9), Korean (11) and African populations, TMPT*3C is the most prevalent mutant allele (7, 10) while in Latin-American population it was not detected at all (8). On the other hand the TPMT*2 allele is present in 9.4 % of mutant alleles in British population, while being very rare in Slovak IBD patients and not present in any of Ghanaian subjects (2).…”

Section: Discussionmentioning

confidence: 99%

Prevalence of mutations in thiopurine S-methyltransferase gene among Slovak IBD patients

Desatova

Hlavatý²,

Balakova³

et al. 2013

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Abstract:Background: Thiopurine S-methyltransferase (TPMT) plays an important role in the metabolism of thiopurines. It has been suggested that TPMT genetic polymorphisms lead to dose-related hematopoietic toxicity. Since there are major ethnic differences in the prevalence of particular TPMT variants, it is important for each country to study their own prevalence in order to estimate the role of TPMT variants-related thiopurines toxicity in population suffering from particular infl ammatory bowel disease (IBD). Aims: The aim of this study was to determine the frequency of the four most common allelic variants of TPMT gene in the population of Slovak IBD patients. Methods: TPMT genetic polymorphisms (TPMT*2, TPMT*3A, TPMT*3B, TPMT*3C) were amplifi ed using PCR and consequently genotyped with genetic analyzer. The allele frequencies of particular allelic variants were calculated and compared with other Caucasian populations reported so far. Results: Three hundred and thirty IBD patients were included; 196/132/2 cases of Crohn´s disease/ulcerative colitis/unclassifi ed colitis; 180 (55 %) males. Ninety-three percent of patients were homozygous for wild-type TPMT variant. Heterozygous genotype of any of the studied polymorphisms was present in 6 % of patients while only one patient was homozygous for TPMT*3A allele (0.3 %). The most prevalent mutant allele was that of TPMT*3A (3.2 %). The distribution of most common allelic variants of TPMT gene among Slovak IBD patients was in accordance with previously reported prevalence in Caucasian populations. Conclusion: This study shows the prevalence of TPMT genetic polymorphisms in population of Slovak IBD patients. As in other Caucasian populations, the most common mutant allelic variant is that of TPMT*3A while the prevalence of homozygosity is relatively low (Tab. 3, Ref. 22). Full Text in PDF www.elis.sk.

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“…Además hubo un individuo con genotipo heterocigoto (3A) que tuvo una actividad normal de 28,2 nmol/ gHb/h (Figura 2). La distribución de la actividad enzimática en nuestra muestra sigue un patrón bimodal, descrito en otras poblaciones, según su genotipo 12,14,17,18,24 .…”

Section: Frecuencia De Los Polimorfi Smos De La Tpmtunclassified

“…Existen diferencias étnicas en las frecuencias de variantes genéticas para la TPMT 10,16 . Esto ha sido escasamente estudiado en población latinoamericana mestiza, sin una adecuada descripción del grado de mezcla hispánica y amerindia 17,18 . En Chile no existen recomendaciones basadas en estudios locales de correlación genotipo- fenotipo, lo que puede contribuir a una dosifi cación insufi ciente de tiopurínicos por largos períodos, por lo que conocer su estado permitirá dar recomendaciones más efi cientes y seguras.…”

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Genotipo y fenotipo de la enzima tiopurina metiltransferasa en población chilena

et al. 2012

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Allelic variants of the thiopurine methyltransferase (TPMT) gene in the Colombian population

Cited by 32 publications

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The low frequency of defective TPMT alleles in Turkish population: A study on pediatric patients with acute lymphoblastic leukemia

The low frequency of defective TPMT alleles in Turkish population: A study on pediatric patients with acute lymphoblastic leukemia

Prevalence of mutations in thiopurine S-methyltransferase gene among Slovak IBD patients

Genotipo y fenotipo de la enzima tiopurina metiltransferasa en población chilena

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