title: Association Between 5-HTTLPR Polymorphism and Tics after Treatment with Methylphenidate in Korean Children with Attention-Deficit/Hyperactivity Disorder.
abstract: OBJECTIVE
  The purpose of this study is to examine the relationship between 5-HTTLPR polymorphism (44-bp insertion/deletion polymorphism of serotonin transporter gene) and methylphenidate (MPH) treatment response, as well as the association between the adverse events of MPH treatment and 5-HTTLPR polymorphism in children with attention-deficit/hyperactivity disorder (ADHD).
  
  
  METHODS
  A total of 114 children with ADHD (mean age 9.08 ± 1.94 years) were recruited from the child psychiatric clinic in a hospital in South Korea. We have extracted the genomic DNA of the subjects from their blood lymphocytes and analyzed 5-HTTLPR polymorphism of the SLC6A4 gene. All children were treated with MPH for 8 weeks, with clinicians monitoring both the improvement of ADHD symptoms and the side effects. We compared the response to MPH treatment and adverse events among those with the genotype of 5-HRRLPR polymorphism.
  
  
  RESULTS
  There was no significant association between the 5-HTTLPR genotype and the response to MPH treatment in children with ADHD. Subjects with the S/L+L/L genotype tended to have tics and nail biting (respectively, p < 0.001, p = 0.017).
  
  
  CONCLUSIONS
  The results of this study do not support the association between the 5-HTTLPR polymorphism and treatment response with MPH in ADHD. However, our findings suggest the association between 5-HTTLPR polymorphism and the occurrence of tics and nail-biting as an adverse event of methylphenidate. This may aid in our understanding of the genetic contribution and genetic susceptibility of a particular allele in those ADHD patients with tics or nail biting.
authors.affiliation: Department of Psychiatry and Institute of Behavioral Science in Medicine, Yonsei University College of Medicine , Seoul, Korea.
authors.forename: Seo Yeon
authors.initials: SY
authors.lastname: Park
authors.affiliation: Department of Psychiatry and Institute of Behavioral Science in Medicine, Yonsei University College of Medicine , Seoul, Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Kim
authors.affiliation: Department of Psychiatry and Institute of Behavioral Science in Medicine, Yonsei University College of Medicine , Seoul, Korea.
authors.forename: Keun-Ah
authors.initials: KA
authors.lastname: Cheon
mesh_terms: D000293:Adolescent; D000483:Alleles; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000009:adverse effects / Q000627:therapeutic use; D002648:Child; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000009:adverse effects* / Q000627:therapeutic use*; D009259:Nail Biting; D011110:Polymorphism, Genetic / Q000235:genetics; D056910:Republic of Korea; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D020323:Tics / Q000139:chemically induced* / Q000150:complications / Q000235:genetics*; D016896:Treatment Outcome
chemical_list: D000697:Central Nervous System Stimulants; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D008774:Methylphenidate