title: Haplotype and nucleotide variation in the exon 3-VNTR of the DRD4 gene from indigenous and urban populations of Mexico.
abstract: OBJECTIVE
  To describe the population structure of the 48-bp variable number of tandem repeats (VNTR), located in exon 3 of the dopamine receptor D4 gene (DRD4), in 41 Tarahumara from northern Mexico, 20 Mixe from southern Mexico, and 169 people from Mexico City.
  
  
  METHODS
  Genotypes for the DRD4-VNTR were determined, from which 15 Tarahumara, eight Mixe, and 37 urban homozygous individuals were sequenced. Repeat-allele frequencies were compared with other world populations.
  
  
  RESULTS
  The DRD4-VNTR variation in Mexico City appeared similar to the world mean. For the Mixe and Maya, DRD4-VNTR diversity appeared closer to South American groups whereas the Tarahumara were similar to North American groups. People from Mexico City and the Mixe exhibited attributes of a large and admixed population and an isolated population, respectively. The Tarahumara showed endogamy associated with a substructure as suggested by a preliminary regional differentiation. For the DRD4-VNTR and/or the adjacent 5'-173 bp sequence, the three populations exhibited negative Tajima's D. Two new VNTR haplotypes were discovered: one in Mexico City and another among the Tarahumara.
  
  
  CONCLUSIONS
  A differentiation in the DRD4-VNTR of global relevance occurs between northern and southern populations of Mexico suggesting that the Mexican Trans-volcanic Belt has been a major frontier for human dispersion in the Americas. Ancient trespass of this barrier appears thus related to a major change in the population structure of the DRD4-VNTR. Distinctive and independent patterns of DRD4-VNTR diversity occur among the two Mexican indigenous populations by a still undefined combination of drift and selection.
authors: Departamento de Genética Psiquiátrica, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, México, DF, México; Laboratorio de Antropología Genética, Instituto de Investigaciones Antropológicas, Universidad Nacional Autónoma de México, México, DF, México; Programa de Becas Posdoctorales, Coordinación de Humanidades, Instituto de Investigaciones Antropológicas, Universidad Nacional Autónoma de México, México, DF, México.
authors: Ana Julia
authors: AJ
authors: Aguirre-Samudio
authors: Carlos Sabás
authors: CS
authors: Cruz-Fuentes
authors: Blanca Zoila
authors: BZ
authors: González-Sobrino
authors: Verónica
authors: V
authors: Gutiérrez-Pérez
authors: Luis
authors: L
authors: Medrano-González
mesh_terms: D005091:Exons; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D007198:Indians, North American; D008800:Mexico; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D050638:Receptors, Dopamine D4 / Q000097:blood / Q000235:genetics*; D012463:Saliva / Q000737:chemistry; D017422:Sequence Analysis, DNA; D014505:Urban Population
chemical_list: C493599:DRD4 protein, human; D050638:Receptors, Dopamine D4