The influence of DRD4 genotype and perinatal complications on preschoolers' negative emotionality

This study investigated the influence of the DRD4 gene and the perinatal environment on child temperament in 5-year-old twins. Participants were 94 twin or triplet sets (101 girls, 89 boys). Parents completed questionnaires about children's birth complications (BC) when children were 1 or 2 years old and temperament questionnaires assessing negative emotionality (NE) when children were 5. DRD4 genotype was determined from children's buccal cells. A significant interaction between BC and DRD4 genotype predicted children's NE. For children without the DRD4 7-repeat allele, those with more moderate BC had high levels of NE; those with the fewest moderate BC showed significantly less NE. This did not hold for children with the 7-repeat allele. Additionally, minor BC significantly predicted NE for all children, regardless of genotype, whereas severe BC did not. This study underlines the importance of including NE during the preschool years as a possible risk outcome for birth complications.