The association between 5-HTTLPR gene polymorphism and behavioral inhibition in Chinese toddlers.

As one of the fundamental individual characteristics, behavioral inhibition in early childhood has considerable implications for the development of social, cognitive, and psychological adjustment. The purpose of this study was to examine the relation between the 5-HTTLPR polymorphism and behavioral inhibition in Chinese children using a cross-sectional design. A sample of 263 2-year-old children (134 boys and 129 girls of Han ethnicity; ages ranging from 24 to 26 months) in China participated in the study. Behavioral inhibition was assessed through laboratory observations, and genomic DNA was collected with buccal swabs. The results of analysis of covariance (ANCOVA) indicated that the homozygous short 5-HTTLPR allele was associated with lower levels of behavioral inhibition, which was different from most of the findings based on individuals in Western countries. The results suggest that social and cultural factors may be involved in shaping links between the 5-HTTLPR polymorphism and children's specific behaviors.