title: BDNF Val66Met polymorphism and stressful life events in melancholic childhood-onset depression.
abstract: BACKGROUND
  Brain-derived neurotrophic factor (BDNF) polymorphisms have been examined for their contribution toward depression with equivocal results. More homogeneous phenotypes might be used to improve our understanding of genetic liability to depression. The aim of our study was to (a) test for an association between the BDNF Val66Met polymorphism and childhood-onset melancholic depression and (b) to examine the interactive effects of stressful life events (SLE) and the Val66Met polymorphism on the risk of childhood-onset melancholic depression.
  
  
  METHODS
  A total of 583 depressed probands were involved in this study (162 of the melancholic subtype). Diagnoses were derived through the Interview Schedule for Children and Adolescents - Diagnostic Version and life event data were collected using an Intake General Information Sheet.
  
  
  RESULTS
  Overall, 27.8% of the participants fulfilled the criteria for melancholy. In the melancholic group, the proportion of females was higher (53.1%), although there were more males in the overall depressed sample. We detected no significant differences in genotype or allele frequency between the melancholic and the nonmelancholic depressed group. The BDNF Val66Met polymorphism and SLE interaction was not significantly associated with the melancholy outcome.
  
  
  CONCLUSIONS
  In our study, females were more prone to developing the early-onset melancholic phenotype. To our knowledge, this is the first study to investigate the differentiating effect of the genotype and the G×E interaction on the melancholic phenotype in a large sample of depressed young patients. We did not find an association between the melancholic subtype of major depression and the BDNF genotype and SLE interaction in this sample, which is representative of the Hungarian clinic-referred population of depressed youths.
authors.affiliation: aChild and Adolescent Psychiatry Unit, Department of Pediatrics bDepartment of Psychiatry, University of Szeged, Szeged, Hungary cCentre for Addiction and Mental Health, University of Toronto dUniversity Health Network, Toronto Western Research Institute, Toronto, Ontario, Canada eDepartment of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors.forename: Timea
authors.initials: T
authors.lastname: Rimay
authors.forename: Istvan
authors.initials: I
authors.lastname: Benak
authors.forename: Eniko
authors.initials: E
authors.lastname: Kiss
authors.forename: Ildiko
authors.initials: I
authors.lastname: Baji
authors.forename: Agnes
authors.initials: A
authors.lastname: Feher
authors.forename: Anna
authors.initials: A
authors.lastname: Juhasz
authors.forename: John
authors.initials: J
authors.lastname: Strauss
authors.forename: James
authors.initials: J
authors.lastname: Kennedy
authors.forename: Cathy
authors.initials: C
authors.lastname: Barr
authors.forename: Maria
authors.initials: M
authors.lastname: Kovacs
authors.forename: Agnes
authors.initials: A
authors.lastname: Vetro
authors.forename: Krisztina
authors.initials: K
authors.lastname: Kapornai
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D002648:Child; D003865:Major Depressive Disorder / Q000453:epidemiology / Q000235:genetics* / Q000523:psychology*; D005260:Female; D006801:Humans; D006814:Hungary / Q000453:epidemiology; D008016:Life Change Events; D008297:Male; D008715:Methionine / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D014633:Valine / Q000235:genetics
chemical_list: D019208:Brain-Derived Neurotrophic Factor; C579455:BDNF protein, human; D008715:Methionine; D014633:Valine