Dopamine D4 receptor (DRD4) gene polymorphism is associated with attachment disorganization in infants

About 15% of one-year-old infants in non-clinical, low-risk and up to 80% i n high-risk leg maltreated) populations show extensive disorganized attachm ent behavior(1,2) in the Strange Situation Test.(3) It has also been report ed that disorganization of early attachment is a major risk factor for the development of childhood behavior problems.(4) The collapse of organized at tachment strategy has been explained primarily by inappropriate caregiving, but recently, the contribution of child factors such as neurological impai rment(5) and neonatal behavioral organization(6) has also been suggested. H ere we report an association between the DRD4 III exon 48-bp repeat polymor phism and attachment disorganization, Attachment behavior of 90 infants was tested in the Strange Situation and they were independently genotyped for the number of the 48-bp repeats by polymerase chain reaction (PCR), The 7-r epeat allele was represented with a significantly higher frequency in infan ts classified as disorganized compared to non-disorganized infants: 12 of 1 7 (71%) vs 21 of 73 (29%) had at least one 7-repeat allele (chi (2) = 8.66, df = 1, P < 0,005). The estimated relative risk for disorganized attachmen t among children carrying the 7-repeat allele was 4.15. We suggest that, in non-clinical, low-social-risk populations, having a 7-repeat allele predis poses infants to attachment disorganization.