OBJECTIVETo investigate the association between dopamine D4 receptor gene DRD4 exon III 48bp variable number of tandem repeat (VNTR) polymorphism and temperament in school-aged children.

METHODSRandomized cluster sampling was used to select 350 healthy children aged 8-12 years, and a questionnaire survey was performed. Oral epithelial samples were collected from half of these children. The complete questionnaire data of 164 children with a high level of DNA in oral epithelial samples were included in this study. PCR was used for the typing of DRD4 exon III 48bp VNTR, and the effect of this gene and its interaction with the environment on temperament was analyzed.

RESULTSCompared with the children with S-DRD4 genotype, the children with L-DRD4 genotype had significantly lower scores on the four dimensions of activity level, reaction intensity, emotion essence, and persistence (P<0.05). The main effects of mother's rejection/denial (OR=2.281, P<0.05) and sex (OR=2.766, P<0.05) and the interaction between sex and DRD4 exon III 48bp VNTR (OR=0.582, P<0.05) had an influence on activity level. The main effect of DRD4 exon III 48bp VNTR (OR=0.314, P<0.01) and the interaction between this gene and mother's rejection/denial (OR=1.872, P<0.01) had an influence on reaction intensity. The main effect of DRD4 exon III 48bp VNTR (OR=0.420, P<0.05) and mother's rejection/denial (OR=2.236, P<0.05) had an influence on persistence.

CONCLUSIONSDRD4 exon III 48bp VNTR and its interaction with other factors may affect the activity level and reaction intensity of school-aged children.