ABSTRACT
<p><b>OBJECTIVE</b>To investigate the mRNA expression of dopamine receptor D2 (DRD2) and dopamine transporter (DAT) in peripheral blood lymphocytes before and after treatment in children with tic disorder (TD).</p><p><b>METHODS</b>RT-PCR was used to measure the mRNA expression of DRD2 and DAT in peripheral blood lymphocytes before and after treatment in 60 children with TD. The correlations between mRNA expression of DRD2 and DAT and the severity of TD were analyzed. Sixty healthy children served as the control group.</p><p><b>RESULTS</b>Before treatment, the children with TD had a significant increase in the mRNA expression of DRD2 and DAT compared with the control group (P<0.05). After 3 months of treatment with oral aripiprazole, the mRNA expression of DRD2 decreased significantly (P<0.05), while that of DAT showed no significant changes in children with TD. In the children with moderate or severe TD, the mRNA expression of DRD2 was positively correlated with Yale Global Tic Severity Scale (YGTSS) score (P<0.05). In the children with moderate TD, the mRNA expression of DAT was positively correlated with YGTSS score (P<0.05).</p><p><b>CONCLUSIONS</b>In children with TD, the mRNA expression of DRD2 in peripheral blood lymphocytes can be used as one of the indicators for diagnosing TD, assessing the severity of TD, and evaluating clinical outcomes.</p>