Lack of association between response of OROS-methylphenidate and norepinephrine transporter (SLC6A2) polymorphism in Korean ADHD

This study investigated the relationship between the five common polymorphisms (rs2242446, rs5568, rs5569, rs998424, and rs1616905) in the norepinephrine transporter (NET) gene and the OROS-methylphenidate response in a medication-naïve Korean attention-deficit hyperactivity disorder (ADHD) sample. One hundred thirty-seven patients with ADHD were recruited from the child and adolescent psychiatric outpatient units. The trial was an eight-week, open-label study of OROS-methylphenidate monotherapy, and treatment outcomes were measured using the Korean version of the ADHD Rating Scales-IV (K-ARS) for the parents, the Clinician Global Impression Severity Scale (CGI-S) and the Clinician Global Impression Improvement Scale (CGI-I). Associations between the five NET polymorphisms and the drug response were analyzed using genotype and allele frequencies at each locus. There was no significant difference in genotype and allele distribution for each NET polymorphism between responders and non-responders (P > 0.05). There were no significant differences in change of the K-ARS score, change of CGI-S scores or CGI-I scores at 8 weeks among each genotype and allele of five NET polymorphisms (P > 0.05). Although there were no significant positive results, our findings may have several implications and offer direction for future studies.