No significant association between the alpha-2A-adrenergic receptor gene and treatment response in combined or inattentive subtypes of attention-deficit hyperactivity disorder.
INTRODUCTION
Given the shortage of pharmacogenetic studies on treatment response according to subtype of attention-deficit hyperactivity disorder (ADHD), we investigated the associations between the MspI and DraI polymorphisms of the alpha-2 A-adrenergic receptor gene (ADRA2A) and treatment response to methylphenidate according to subtype of ADHD.


METHODS
We enrolled 115 medication-naïve children with ADHD into an open label 8-week trial of methylphenidate. The participants were genotyped and evaluated using the Clinical -Global Impression (CGI), ADHD rating scale, and Continuous Performance Test (CPT) pre- and post-treatment.


RESULTS
There was no statistically significant association between the MspI or DraI genotypes and the relative frequency of CGI-improvement (CGI-I) 1 or 2 status among any of the groups (all types of ADHD, ADHD-C, or ADHD-I). However, among the children with ADHD-C, those subjects with the C/C genotype at the ADRA2A DraI polymorphism tended to have a CGI-I 1 or 2 status post-treatment (OR=4.45, p=0.045).


DISCUSSION
The results of this study do not support the association between the the MspI or DraI genotypes and treatment response to methylphenidate in ADHD. However, our results -suggest that subtypes might influence pharmacogenetic results in ADHD.·available online at http://www.thieme-connect.de/ejournals/toc/pharmaco.