BACKGROUND AND OBJECTIVES

Most genetic studies have focused on catecholamine system genes to identify etiology in attention-deficit/hyperactivity disorder (ADHD), and there is growing evidence that the interaction of several genes may synergistically or antagonistically affect disease outcomes. We investigated the interaction between the alpha-2 adrenergic receptor () and its transporter () to determine the etiology and treatment outcomes for ADHD.

MATERIALS AND METHODS

Children with ADHD (age 8.3 ± 2.0 y, 72 boys and 11 girls) were assessed using the Kiddie Schedule for Affective Disorders-Present and Lifetime (K-SASD-PL), ADHD rating scale-IV (ARS), Clinical Global Impressions-Improvement (CGI-I), and Clinical Global Impressions-Severity (CGI-S) scales. Neuropsychological assessments were performed using a continuous performance test (CPT). Methylphenidate was titrated based on the CGI-I and CGI-S scales for 8 weeks. We assessed two polymorphisms, rs553668 and rs998424, for their association with disease outcomes.

RESULTS

The polymorphism had a significant effect on visual/auditory commission errors in the CPT. The CC genotype for combined with the GG genotype for showed more commission errors than the other combinations of genotypes. Treatment outcome assessment using the CGI-S showed that the GG genotype had more favorable treatment outcome ( < 0.05) and significant gene × dose interaction on ARS score across 8 weeks ( < 0.01).

CONCLUSIONS

Our findings provide preliminary evidence for the effect of and gene-gene interactions on the attention system and treatment response in children with ADHD. Although these findings require future replication, our study contributes to the understanding of the genetic basis of ADHD.