title: Thiopurine methyltransferase phenotypes and genotypes in Brazilians.
abstract: The polymorphism of thiopurine methyltransferase (TPMT) was studied in 306 healthy Brazilians who were classed, on the basis of self-declared colour and ancestry, as Euro-derived (n = 81), Afro-derived (n = 18) or having interethnic admixture (n = 204). TPMT activity (range 0.17-25.93 U) displayed a trimodal distribution of high (> 11.3 U; 9% of individuals), intermediate (5-11.3 U; 9.8%) and low (0.17 U; 0.3%) phenotypes. The occurrence of the TPMT mutations 238G>C, 460G>A and 719A>G was investigated in all individuals with low or intermediate phenotype, and in 43 with high-activity phenotype. None and two mutant alleles were associated with high- or low-activity phenotypes, respectively, whereas one mutant allele was detected in 26 of the 30 intermediate phenotype individuals. The allele frequencies of TPMT*2, TPMT*3A and TPMT*3C did not differ between individuals classed as Euro-derived (0.76%, 2.03% and 2.54%, respectively) or having interethnic admixture (0.60%, 1.81% and 1.81%, respectively). Furthermore, within each of these groups, the frequencies of TPMT*3A and TPMT*3C were not significantly different.
authors.affiliation: Divisão de Farmacologia, Coordenação de Presquisa, Instituto Nacional de Câncer, Rio de Janeiro, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Reis
authors.forename: Ana
authors.initials: A
authors.lastname: Santoro
authors.forename: Guilherme
authors.initials: G
authors.lastname: Suarez-Kurtz
mesh_terms: D001741:Black or African American / Q000235:genetics; D001938:Brazil; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D008780:Methyltransferases / Q000235:genetics*; D010641:Phenotype; D044465:White People / Q000235:genetics
chemical_list: D008780:Methyltransferases; C022745:thiopurine methyltransferase