title: Dopaminergic, serotonergic, and oxytonergic candidate genes associated with infant attachment security and disorganization? In search of main and interaction effects.
abstract: METHODS
  In two birth cohort studies with genetic, sensitive parenting, and attachment data of more than 1,000 infants in total, we tested main and interaction effects of candidate genes involved in the dopamine, serotonin, and oxytocin systems (DRD4, DRD2, COMT, 5-HTT, OXTR) on attachment security and disorganization. Parenting was assessed using observational rating scales for parental sensitivity (Ainsworth, Bell, & Stayton, 1974), and infant attachment was assessed with the Strange Situation Procedure.
  
  
  RESULTS
  We found no consistent additive genetic associations for attachment security and attachment disorganization. However, specific tests revealed evidence for a codominant risk model for COMT Val158Met, consistent across both samples. Children with the Val/Met genotype showed higher disorganization scores (combined effect size d = .22, CI = .10-.34, p < .001). Gene-by-environment interaction effects were not replicable across the two samples.
  
  
  CONCLUSIONS
  This unexpected finding might be explained by a broader range of plasticity in heterozygotes, which may increase susceptibility to environmental influences or to dysregulation of emotional arousal. This study is unique in combining the two largest attachment cohorts with molecular genetic and observed rearing environment data to date.
authors.affiliation: Center for Child and Family Studies, Leiden University, Leiden, The Netherlands.
authors.forename: Maartje P C M
authors.initials: MP
authors.lastname: Luijk
authors.forename: Glenn I
authors.initials: GI
authors.lastname: Roisman
authors.forename: John D
authors.initials: JD
authors.lastname: Haltigan
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
authors.forename: Cathryn
authors.initials: C
authors.lastname: Booth-Laforce
authors.forename: Marinus H
authors.initials: MH
authors.lastname: van Ijzendoorn
authors.forename: Jay
authors.initials: J
authors.lastname: Belsky
authors.forename: Andre G
authors.initials: AG
authors.lastname: Uitterlinden
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Frank C
authors.initials: FC
authors.lastname: Verhulst
authors.forename: Anne
authors.initials: A
authors.lastname: Tharner
authors.forename: Marian J
authors.initials: MJ
authors.lastname: Bakermans-Kranenburg
mesh_terms: D002394:Catechol O-Methyltransferase / Q000235:genetics*; D002648:Child; D002653:Child Behavior Disorders / Q000235:genetics* / Q000523:psychology; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007223:Infant; D008297:Male; D009034:Mother-Child Relations; D009483:Neuropsychological Tests; D009769:Object Attachment; D011110:Polymorphism, Genetic; D019962:Reactive Attachment Disorder / Q000235:genetics* / Q000523:psychology*; D017448:Receptors, Dopamine D2 / Q000235:genetics; D050638:Receptors, Dopamine D4 / Q000235:genetics; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics
chemical_list: C493599:DRD4 protein, human; D017448:Receptors, Dopamine D2; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D050638:Receptors, Dopamine D4; D002394:Catechol O-Methyltransferase