Allele frequencies of dopamine D4 receptor gene (DRD4) and Catechol-Omethyltransferase (COMT) Val158Met polymorphism are associated with methylphenidate response in adolescents with attention deficit/hyperactivity disorder: a case control preliminary study

Abstract

OBJECTIVES: In this study, it was aimed to analyse the relationship between clinical improvement in adolescents with attention deficit/hyperactivity disorder (ADHD) and the presence of allele frequencies of dopamine D4 receptor (DRD4), and Val158Met polymorphism of catechol-O-methyltransferase (COMT) genes.

METHODS: Thirty-four adolescents (age range, 13–18 years) with ADHD participated in this study. Thirty-two patients were males and two were females. Du Paul ADHD Rating ScaleClinician version (ARS) and Clinical Global Impression-severity of impairment (CGI-S) were used for the evaluation of symptom severity. Fifty healthy age-matched adolescents were recruited as controls.

RESULTS: When the groups with (n = 9) and without (n = 25) 7-repeat alleles for DRD4 were considered, there was a statistically significant decrease of DuPaul ARS total and hyperactivity scores in those treated with OROS-methylphenidate. When the Val/Met allelepositive group for COMT gene (n = 17) was compared with the Val/Val allele-positive group (n = 13) and Met/Met allele-positive group (n = 4), there was a statistically significant decrease of ARS total scores, ARS attention scores, and CGI scores in adolescents with ADHD treated with OROS-MPH.

CONCLUSIONS: Specific data from further studies with a larger sample sizes would provide more insights to replicate the current findings.