An exploratory genetic analysis: Associations between parent depression symptoms, child temperament, and the serotonin transporter gene polymorphism (5HTTLPR)

Child temperament has been shown to be biologically based and heritable; however, genetic association studies of temperament have been fairly inconclusive, and the role that parental depressive symptoms play is largely unexplored in this context. The relationship between parent depressive symptoms and the child temperament dimensions of fear and activity level (AL) were examined in 100 sibling pairs 2.5–5.5 years of age and their mothers. Parent reports of child temperament and parent self-reports of depressive symptoms were obtained from families, as well as DNA samples from each child during their lab visit. Associations between the serotonin transporter gene (SLC6A4) polymorphism 5-HTTLPR/rs25531 and the phenotypic variables were also explored. Parent depressive symptoms were significantly related to higher child AL, but minimally associated with fear outcomes. More powerful regression analyses revealed that parent depressive symptoms, child gender, and child age predicted child AL, but only child gender and age predicted child fear. In our exploratory candidate gene analyses, the low-expressing genotypes of the 5-HTTLPR/rs25531 polymorphism predicted child fearfulness, but not child AL. Our phenotypic findings indicate that a child with at least one parent with depressive symptoms is more likely to have higher AL, and results of the initial genetic analyses show that the 5-HTTLPR/rs25531 polymorphism is associated with child fearfulness. Future research employing larger samples, observational assessments, and related child behavioral maladjustment measures will further clarify these findings.