DRD4 dopamine receptor alleles in Chilean students of different ethnic origin and its relation with the risk for attention deficit/hyperactivity disorder
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
SOC MEDICA SANTIAGO
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. Aim: To study the association of ADHD risk with DRD4 genotypes in Chilean students. Subjects and 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. (Rev Med Chile 2012; 140: 1276-1281).
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Keywords
Attention deficit disorder with hyperactivity, Child, Dopamine D4, Receptors, DEFICIT HYPERACTIVITY DISORDER, 2-REPEAT ALLELE, D-4 RECEPTOR, HAPLOTYPE CHARACTERIZATION, GENE LOCUS, ASSOCIATION, SELECTION, FREQUENCIES, RELEVANCE, SEEKING