title: Frequency of genetic polymorphisms of PXR gene in the Brazilian population.
abstract: BACKGROUND
  PXR polymorphisms have been implicated in modulating CYP3A4 and PXR expression, potentially accounting for interindividual differences in drug metabolism. The prevalence of PXR polymorphisms varies among ethnic groups and data on the allelic distribution in the highly mixed Brazilian population is lacking. The aim of this study was to analyze genetic variations in the PXR gene in Brazilians and to compare the results to other ethnic groups.
  
  
  METHODS
  DNA samples from 117 healthy Brazilians underwent PCR amplification and sequencing.
  
  
  RESULTS
  Eleven polymorphisms were identified, 3 of which are highly associated with differences in CYP3A4 expression. We also identified 1 new synonymous variant in 1.3% of the alleles. Among the functional polymorphisms, -25913 C>T and -6994T>C occurred at a higher frequency comparedtothe Africanalleles (p < 0.05) but at a lower frequency compared to Caucasian alleles. The 8055 C>T allele was found at a similar frequency to those described in Caucasians and Africans (p > 0.05).
  
  
  CONCLUSIONS
  We observed that functional variants of the PXR were frequent in our sample of the Brazilian population. Our results suggest that PXR gene variants may be of interest in pharmacogenetic studies involving Brazilians.
authors.affiliation: Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM 42, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Ricardo P P
authors.initials: RP
authors.lastname: Moreira
authors.forename: Alexander A L
authors.initials: AA
authors.lastname: Jorge
authors.forename: Berenice B
authors.initials: BB
authors.lastname: Mendonca
authors.forename: Tânia A S S
authors.initials: TA
authors.lastname: Bachega
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D001938:Brazil / Q000208:ethnology; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D005006:Ethnicity / Q000235:genetics; D005091:Exons; D005260:Female; D005787:Gene Frequency; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid / Q000235:genetics*; D055815:Young Adult
chemical_list: D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human