title: [Polymorphisms of the multiple drug resistance gene (MDR1) in Mapuche, Mestizo and Maori populations in Chile].
abstract: BACKGROUND
  There are significant differences in drug responses among different ethnic groups. The multidrug transporter P-gp, encoded by the MDR1 gene, plays a key role in determining drug bioavailability, and an association between a polymorphism in exon 26 (C3435T) and lower P-gp expression has been found. The co-segregation of this polymorphism with the polymorphism in exon 12 (C1236T) and in exon 21 (G2677T/A) determines several MDR1 haplotypes in humans.
  
  
  OBJECTIVE
  To characterize the polymorphisms of exons 26, 21 and 12 of the MDR1 gene in different Chilean populations.
  
  
  METHODS
  Using a polymerase chain reaction and restriction fragment length polymorphism technique, we studied the allelic frequencies and the distribution of MDR1 haplotypes in 3 Chilean populations: Mestizo (n=104), Mapuche (n=96, living in the National Reservation of the Huapi Island, Ranico Lake) and Maori (n=52, living in Eastern Island).
  
  
  RESULTS
  The frequency of the normal MDR1*1 haplotype, without mutations, was lower in Mapuches than in Mestizos or Maoris (p<0.005) but similar to that reported in Asian population (p=0.739), probably due to the Asian origin of the Amerindian populations. In addition, the MDR1*l haplotype fequency hin Mestizos was similar to the frequency reported in Caucasians (p=0.49), in agreement with the origin of our population, with a strong influence of Caucasian genes from the Spanish conquerors. The MDR1*2 haplotype distribution, with the three polymoyphisms and probably lower multidrug transporter expression, was similar in the three Chilean populations studied (p>0.0.5), but lower than the frequencies reported in Caucasians or Asians (p<0.05).
  
  
  CONCLUSIONS
  We found significant differences in the frequencies of genetic polymorphisms of the MDR1 gene in Chilean populations, related to the ethnic origins of our ancestors.
authors.affiliation: Departamento de Gastroenterología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Wielandt
authors.forename: Valeska
authors.initials: V
authors.lastname: Vollrath
authors.forename: José
authors.initials: J
authors.lastname: Chianale
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D002677:Chile / Q000208:ethnology; D005091:Exons / Q000235:genetics*; D005787:Gene Frequency / Q000235:genetics; D019450:Genes, MDR / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D007199:Indians, South American / Q000235:genetics*; D011110:Polymorphism, Genetic
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1