title: [Thiopurine S-methyltransferase gene polymorphism in Chilean blood donors].
abstract: BACKGROUND
  Thiopurine S-methyltransferase (TPMT) is a cytosolic enzyme that catalyzes the S-methylation of 6-mercaptopurine and azathioprine. Low-activity phenotypes are correlated with polymorphism in the TPMT gene. Patients with low or undetectable TMPT activity could develop severe myelosuppression when they are treated with standard doses of thiopurine drugs. Since ethnic differences in the TPMT gen polymorphism have been demonstrated worldwide, its assessment in the Chilean population is worthwhile.
  
  
  OBJECTIVE
  To investigate the TMPT gene polymorphism in a Chilean blood donor individuals.
  
  
  METHODS
  The frequency of four allelic variants of the TPMT gene, *2 (G238C), *3A (G460A and A719G), *3B (G460A) and *3C (A719G) were analyzed in 210 Chilean blood donors, using polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and allele-specific PCR-based assays.
  
  
  RESULTS
  TPMT variants associated to low enzymatic activity, were detected in 16 subjects (8%), who had a heterozygous genotype (*3A in 12; *3C in three and *2 in one subject). No TPMT*3B allelic variant was found. The normal allele (wild-type) was found in 92% of studied individuals.
  
  
  CONCLUSIONS
  The allele TPMT*3A, is the most prevalent in this group of Chilean blood donors, as in Caucasian populations.
authors: Sección de Gastroenterología, Departamento de Medicina Interna, Hospital Clínico Universidad de Chile.
authors: Luis
authors: L
authors: Alvarez L
authors: Mauricio
authors: M
authors: Venegas S
authors: Milton
authors: M
authors: Larrondo L
authors: Natalia
authors: N
authors: Becerra B
authors: Ariel
authors: A
authors: Castro L
authors: Rodrigo
authors: R
authors: Quera P
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D001782:Blood Donors; D002677:Chile / Q000208:ethnology; D005260:Female; D005787:Gene Frequency; D018740:Genetic Heterogeneity; D005819:Genetic Markers; D006579:Heterozygote; D006801:Humans; D008297:Male; D008780:Methyltransferases / Q000032:analysis / Q000235:genetics*; D008875:Middle Aged; D010641:Phenotype; D011110:Polymorphism, Genetic; D055815:Young Adult
chemical_list: D005819:Genetic Markers; D008780:Methyltransferases; C022745:thiopurine methyltransferase