ABSTRACT
<p><b>OBJECTIVE</b>To study the relationship between rs6267 polymorphism of catechol-O-methyltransferase (COMT) gene and attention deficit hyperactivity disorder (ADHD).</p><p><b>METHODS</b>One hundred and fourteen children with ADHD and 76 normal volunteers were enrolled. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques were used for detecting COMT rs6267 polymorphism. The behavioral problems were assessed by Child Behavior Checklist (CBCL).</p><p><b>RESULTS</b>There were no significant differences in the COMT genotype distribution and allele frequencies between the ADHD and normal control groups. The frequencies of thinking problems (1.7±1.9 vs 1.0±0.9) and disciplinary problems (4.5±3.7 vs 2.2±1.4) in ADHD children carrying genotype G/G were significantly higher than those in children carrying G/T (P<0.05).</p><p><b>CONCLUSIONS</b>COMT rs6267 polymorphism may not contribute to susceptibility to ADHD. However, there might be an association between rs6267 polymorphism and some clinical characters of ADHD.</p>