An exploration of common dopaminergic variants and behavior problems in siblings at high risk for autism spectrum disorder

•In high-risk siblings, dopamine genotypes predicted internalizing problems.•Links between genotypes and behavior problems may depend on familial ASD risk.•In this risk context, genotypes may confer risk for additional difficulties.

Younger siblings of children with ASD often exhibit elevated internalizing and externalizing problems. We investigated common dopaminergic variants (DRD4 and DRD2) in relation to behavior problems at 36 months. Genotypes linked to less efficient dopaminergic functioning were associated with higher internalizing problems in high-risk siblings.