ADHDgene Database

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Large-scale studies

Data Summary

Published Variant
- SNP: 1391
- CNV: 398
- Others: 173
Published Gene: 359
Published Region: 128
Pathway by PBA: 8
Study: 361

Study Report

Basic Info

Reference	Roman T, 200312815749
Citation	Roman T., Schmitz M., Polanczyk G. V., Eizirik M., Rohde L. A. and Hutz M. H. (2003) "Is the alpha-2A adrenergic receptor gene (ADRA2A) associated with attention-deficit/hyperactivity disorder?" Am J Med Genet B Neuropsychiatr Genet, 120B(1): 116-20.
Study Design	family-based
Study Type	Candidate-gene association study
Sample Size	96 ADHD children and adolescents and their parents
Predominant Ethnicity	Caucasian
Population	Brazil
Age Group	Children/Adolescents : 4-17 years

Detail Info

Summary	They investigated a sample of 96 Brazilian ADHD children and adolescents and their parents for the ADRA2A MspI polymorphism. Although no association with either MspI allele was observed through the haplotype relative risk (HRR) analysis, effects of the ADRA2A gene on inattention and combined (inattention+hyperactivity/ impulsivity) symptom scores were detected. Their results suggest that the ADRA2A gene might have a small effect on ADHD susceptibility or that this gene might modulate the severity of the disorder.
Total Sample	Ninety-six probands and 169 biological parents were genotyped from 73 mother, father, and affected child trios and 23 parent/affected child pairs. The age of the probands ranged between 4 years and 17 years.
Sample Collection	Patients were drawn from the ADHD outpatient clinic at the Child and Adolescent Psychiatric Division of Hospital de Clinicas de Porto Alegre (HCPA).
Diagnosis Description	A consensus diagnosis of ADHD based on DSM-IV criteria was achieved through a three-stage process, described in detail previously [Roman et al., 2001; Rohde, 2002]. Briefly, it comprised: (a) evaluation with a semi-structured interview (Schedule for Affective Disorders and Schizophrenia for School-Age Children, Epidemiological Version-K-SADS-E) [Orvaschel, 1985], modified to assess DSM-IV criteria and applied to the parents by trained research assistants; (b) discussion of each diagnoses derived through the K-SADS-E in a clinical committee chaired by one of us (L.A.R.); (c) clinical evaluation of ADHD and comorbid conditions using DSM-IV criteria by a child psychiatrist who received previously the results of the K-SADS-E and conducted interviews with parents (usually the mother) and the child or adolescent. In addition, parents completed the Child Behavior Checklist (CBCL), Parent Report Form [Achenbach, 1991]. For probands who were attending school, teachers completed the Attention Problems scale of the CBCL-Teacher Report Form (TRF) [Achenbach, 1991]. The ADHD combined type was the most prevalent (77%), followed by the inattentive type (17%), and the hyperactive/ impulsive type of the disorder (6%).
Technique	High molecular weight genomic DNA was isolated from whole blood lymphocytes by a salting out procedure described by Miller et al. [1988]. The MspI polymorphism in the promoter region of the ADRA2A gene was amplified by the polymerase chain reaction (PCR) using the primers and protocols previously reported [Lario et al., 1997].
Analysis Method	Allele frequencies were estimated by counting. The haplotype relative risk (HRR) statistics [Terwilliger and Ott, 1992] was used for family-based association analysis. Dimensional analyses were performed using findings from a checklist containing the 18 DSM-IV ADHD symptoms (gathered during the clinical evaluation) to construct inattentive, hyperactive/impulsive, and combined mean scores. Since continuous data did not show a normal distribution, they were compared between groups of probands defined by the MspI genotypes through the non-parametric Mann-Whitney U-test. A significance level of 5% was accepted in these comparisons. The statistical tests were carried out using SPSS, version 8.0 for Windows.
Result Description	Although no association with either MspI allele was observed through the haplotype relative risk (HRR) analysis, effects of the ADRA2A gene on inattention and combined (inattention+hyperactivity/ impulsivity) symptom scores were detected (U=222.5, z=2.19, P=0.03; and U=208.5, z=2.32, P=0.02, respectively). Their results suggest that the ADRA2A gene might have a small effect on ADHD susceptibility or that this gene might modulate the severity of the disorder.

SNPs reported by this study (count: 1)

Genes reported by this study (count: 1)