title: No Association between the Response to Methylphenidate and DRD4 Gene Polymorphism in Korean Attention Deficit Hyperactivity Disorder: A Case Control Study.
abstract: OBJECTIVE
  Recently the relationship between alleles frequency distribution, drug response and the attention deficit hyperactivity disorder (ADHD), has been actively researched. We investigated the association between the genetic type, alleles and drug response for the dopamine receptor D4 (DRD4) gene in ADHD patients in Korea.
  
  
  METHODS
  One hundred fourteen patients diagnosed with ADHD according to the the Diagnostic and Statistical Manual of Mental Disorders version IV (DSM-IV) diagnostic criteria were selected for the study. The clinical features of patients were confirmed by Korean version of Conners' parent rating scale, Attention deficit Diagnostic System, Korean version of Spielberger state-trait anxiety scale. Blood samples were taken from the 198 subjects. DNA was extracted from blood lymphocytes, PCR was performed for DRD4 Polymorphism. Alleles, genotype frequencies, the Clinical Global Impression (CGI) improvement score were compared using the chi-square test. Korean ADHD Rating Scale (K-ARS) and CGI severity scores were compared using the t-test.
  
  
  RESULTS
  In comparing the ADHD with 4/4 repeats group and without the ADHD with 4/4 repeats group, no significant difference was seen between the DRD4 genetic type, alleles distribution, and CGI drug response.
  
  
  CONCLUSIONS
  As a result, it is viewed that there is no relationship between ADHD and DRD4, but final decision is indefinite. Follow up studies with larger patient or pure subgroups are expected.
authors.affiliation: Environmental Health Center, Dankoook University Hospital, Cheonan, Korea. ; Department of Psychiatry, Dankook University College of Medicine, Cheonan, Korea.
authors.forename: Hyun Soo
authors.initials: HS
authors.lastname: Ji
authors.forename: Ki Chung
authors.initials: KC
authors.lastname: Paik
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Park
authors.forename: Myung Ho
authors.initials: MH
authors.lastname: Lim
keywords: Attention deficit hyperactivity disorder; Case control studies; DRD4 polymorphism; Drug response; Methylphenidate