Association of the dopamine receptor D4 (DRD4) gene 7-repeat allele with children with attention-deficit/hyperactivity disorder (ADHD): an update.
ABSTRACT Polymorphisms of the dopamine receptor D4 gene DRD4, 11p15.5, have previously been associated with attention-deficit/hyperactivity disorder (ADHD) [Bobb et al., 2005; Am J Med Genet B Neuropsychiatr Genet 132:109-125; Faraone et al., 2005; Biol Psychiatry 57:1313-1323; Thapar et al., 2005; Hum Mol Genet 14 Spec No. 2:R275-R282]. As a follow up to a pilot study [see Castellanos et al., 1998; Mol Psychiatry 3:431-434] consisting of 41 probands and 56 controls which found no significant association between the DRD4 7-repeat allele in exon 3 and ADHD, a greatly expanded study sample (cases n = 166 and controls n = 282) and long term follow-up (n = 107, baseline mean age n = 9, follow-up mean age of n = 15) prompted reexamination of this gene. The DRD4 7-repeat allele was significantly more frequent in ADHD cases than controls (OR = 1.2; P = 0.028). Further, within the ADHD group, the 7-repeat allele was associated with better cognitive performance (measured by the WISC-III) (P = 0.013-0.07) as well as a trend for association with better long-term outcome. This provides further evidence of the role of the DRD4 7-repeat allele in the etiology of ADHD and suggests that this allele may be associated with a more benign form of the disorder.
- SourceAvailable from: Guilherme V. PolanczykClinics (São Paulo, Brazil) 10/2012; 67(10):1125-6. · 1.59 Impact Factor
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ABSTRACT: Attention deficit/hyperactivity disorder (ADHD) is one of the most prevalent childhood psychiatric disorders. During the past decades, studies have focused on its genetic background and the abnormality of the brain structure and function. Recently, an advanced technique linking these two areas, namely, the imaging genetics emerged and kept growing. Imaging genetics primarily identifies genes that influence the brain variations. There are three main strategies of doing an imaging genetic study: using neuroimaging as endophenotypes to find the associated DNA variants, finding neuroimaging effects of risk genes, and hypothesis-free whole-brain voxelwise genome-wide association study. In this review, we begin with demonstrating the basic principles of imaging genetics precisely, with examples from other psychiatric conditions, and then go on to synthesize the existing imaging genetic studies in ADHD. Finally, we elaborate the challenges of applying imaging genetics to ADHD. We conclude that imaging genetics has somewhat showed its potential to provide a more precise understanding of how the genes shape the brain variations and further the clinical features of ADHD.Molecular Neurobiology 04/2014; · 5.47 Impact Factor
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ABSTRACT: The dopaminergic system plays a pivotal role in the central nervous system via its five diverse receptors (D1-D5). Dysfunction of dopaminergic system is implicated in many neuropsychological diseases, including attention deficit hyperactivity disorder (ADHD), a common mental disorder that prevalent in childhood. Understanding the relationship of five different dopamine (DA) receptors with ADHD will help us to elucidate different roles of these receptors and to develop therapeutic approaches of ADHD. This review summarized the ongoing research of DA receptor genes in ADHD pathogenesis and gathered the past published data with meta-analysis and revealed the high risk of DRD5, DRD2, and DRD4 polymorphisms in ADHD.Molecular Neurobiology 05/2012; 45(3):605-20. · 5.47 Impact Factor