DNA Methylation and Allelic Polymorphism at the Dopamine Transporter Promoter Affect Internalizing and Externalizing Symptoms in Preschoolers

The role of the dopamine transporter (DAT) in the onset and maintenance of emotional–behavioral difficulties is recognized in adults, adolescents and school-age children, whereas few studies in this field have focused on preschoolers. The study recruited 2-year old children (N = 152) in the general population assessing the possible effect of DAT methylation and allelic polymorphism on internalizing and externalizing symptoms, also exploring whether epigenetic and genetic variability interact. Our results showed that DAT methylation is significantly associated with all the dimensions of children’s emotional/ behavioral functioning in children carrying 10/10–3/3–8/10 polymorphisms but not in children carrying 9/10–9/9 allele repeats. Understanding the influence of genetic/epigenetic factors on maladaptive emotional/behavioral outcomes in young children, can be of great help in programming effective prevention and intervention plans and can be a valid aid to alleviate psychopathological symptoms before they crystalize into more severe clinical conditions in later life.