title: [DRD4 dopamine receptor alleles in Chilean students of different ethnic origin and its relation with the risk for attention deficit/hyperactivity disorder].
abstract: BACKGROUND
  Worldwide diversity of alleles of D4 receptor gene (DRD4), linked to attention deficit hyperactivity disorder (ADHD), is mostly the result of length and single nucleotide polymorphisms in a 48-bp tandem repeat (VNTR). Alleles containing from two (2R) to eleven (11R) repeats have been identified. The most common are 4R, 7R and 2R.
  
  
  OBJECTIVE
  To study the association of ADHD risk with DRD4 genotypes in Chilean students.
  
  
  METHODS
  ADHD risk data were obtained through the abbreviated Conner's Scale for School Teachers in 66 Aymara children (11 cases and 55 controls), 91 Rapa-Nui children (60 cases ad 31 controls) and 96 children from a mixed urban population from Santiago (51 cases and 45 controls). DNA extracted from saliva was amplified by polymerase chain reaction (PCR) to genotype the DRD4 VNTR.
  
  
  RESULTS
  The distribution of DRD4 alleles reveals that, beneath the 4R allele, 7R exhibits the second highest frequencies in Aymara and Santiago children. In Polynesian children, 2R ranks after 4R. A statistically significant association between ADHD risk and 2R/4R genotype was identified in Polynesian children (p < 0.05; odds ratio = 3.7).
  
  
  CONCLUSIONS
  Different DRD4 genotypes are associated with ADHD phenotype in Chilean populations, probably as a consequence of their initial colonization history.
authors.affiliation: Departamento de Psiquiatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Chile. frothham@med.uchile.cl
authors.forename: Paula
authors.initials: P
authors.lastname: Rothhammer
authors.forename: Liza Paz
authors.initials: LP
authors.lastname: Lagos
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Espinoza-Parrilla
authors.forename: Francisco
authors.initials: F
authors.lastname: Aboitiz
authors.forename: Francisco
authors.initials: F
authors.lastname: Rothhammer
mesh_terms: D000483:Alleles; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics*; D016022:Case-Control Studies; D002648:Child; D002677:Chile; D004298:Dopamine / Q000235:genetics*; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007199:Indians, South American / Q000235:genetics*; D050638:Receptors, Dopamine D4 / Q000235:genetics*; D012307:Risk Factors
chemical_list: C493599:DRD4 protein, human; D050638:Receptors, Dopamine D4; D004298:Dopamine