Genetic and environmental influence on  attachment disorganization.
BACKGROUND
Empirical studies demonstrate that maternal sensitivity is associated with attachment security in infancy, while maternal frightening/frightened behavior is related to attachment disorganization. However, attachment disorganization is also predicted by individual dispositions in infancy. Indeed, recent studies indicate a link between attachment disorganization and DRD4 gene polymorphisms, thus suggesting a genetic vulnerability for attachment disorganization. The aims of our study were twofold, to test a) a possible direct link between molecular genetic variations and attachment disorganization, and b) a possible gene-environment interaction with a moderating effect of early maternal caregiving.


METHODS
Attachment security and disorganization, as well as quality of maternal behavior were assessed in the infants of the Regensburg Longitudinal Study IV (N = 106) at the age of 12 months. DNA samples were collected in order to assess the exon III repeat polymorphism in the coding region and the -521 C/T single nucleotide polymorphism (SNP) in the regulatory region of the DRD4 gene and a repeat polymorphism (5-HTTLPR) in the promoter region of the serotonin transporter gene.


RESULTS
Significant associations were found between attachment disorganization and the short polymorphism of the serotonin transporter gene. Also, a gene-environment interaction indicated that this genetic association was only valid for infants of mothers exhibiting low responsiveness. No other significant genetic associations with attachment disorganization were apparent.


CONCLUSIONS
The study suggests a gene-environment interaction whereby biological determinants of attachment disorganization are moderated by social experiences. Different pathways of the development of attachment disorganization are discussed based on a bio-behavioral model of development.
Spangler
Gottfried
G
Institute of Psychology, University of Erlangen-Nürnberg, Germany. Gottfried.Spangler@phil.uni-erlangen.de
Johann
Monika
M
Ronai
Zsolt
Z
Zimmermann
Peter
P
D000483:Alleles; D005091:Exons / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics / Q000523:psychology; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008425:Maternal Behavior / Q000523:psychology; D018598:Minisatellite Repeats / Q000235:genetics*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D019962:Reactive Attachment Disorder / Q000235:genetics* / Q000523:psychology*; D050638:Receptors, Dopamine D4 / Q000235:genetics*; D012016:Reference Values; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D012931:Social Environment
C493599:DRD4 protein, human; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D050638:Receptors, Dopamine D4