title: Oxytocin receptor gene (OXTR) in relation to loneliness in adolescence: interactions with sex, parental support, and DRD2 and 5-HTTLPR genotypes.
abstract: BACKGROUND
  Recent research has shown that loneliness, a common problem in adolescence, may have a genetic basis. The evidence, though, was limited mostly to serotonin-related and dopamine-related genes. In the present study, we focused on the oxytocin receptor gene (OXTR).
  
  
  METHODS
  Associations were examined in a longitudinal study spanning five annual waves (N=307). The relations between OXTR and loneliness were examined, as well as interactions between OXTR and sex, parental support, 5-HTTLPR genotype, and DRD2 genotype.
  
  
  RESULTS
  Using Latent Growth Curve Modeling, the OXTR genotype was not directly related to loneliness. An OXTR×sex interaction was found. Girls showed a steeper decline in loneliness when they had an A allele compared with girls who were homozygous for the G allele. In addition, a gene-gene interaction or epistasis was observed. Both boys and girls who had at least one A1 allele for the DRD2 gene and also had the GG genotype for the OXTR gene showed stable levels of loneliness over time.
  
  
  CONCLUSIONS
  The present study is the first to show that the GG genotype for the OXTR gene is linked to the development of loneliness in adolescence and that this association is moderated by participants' sex and their genotype for a dopamine-related gene.
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, The Netherlands. g.vanroekel@bsi.ru.nl
authors.forename: Eeske
authors.initials: E
authors.lastname: van Roekel
authors.forename: Maaike
authors.initials: M
authors.lastname: Verhagen
authors.forename: Rutger C M E
authors.initials: RC
authors.lastname: Engels
authors.forename: Luc
authors.initials: L
authors.lastname: Goossens
authors.forename: Ron H J
authors.initials: RH
authors.lastname: Scholte
mesh_terms: D000293:Adolescent; D005260:Female; D059647:Gene-Environment Interaction; D005838:Genotype; D006801:Humans; D008132:Loneliness; D008297:Male; D008957:Models, Genetic; D010290:Parents; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D018045:Receptors, Oxytocin / Q000235:genetics*; D012044:Regression Analysis; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D012727:Sex Characteristics
chemical_list: C581293:DRD2 protein, human; C569600:OXTR protein, human; D017448:Receptors, Dopamine D2; D018045:Receptors, Oxytocin; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins