RESUMEN
<p><b>OBJECTIVE</b>To investigate the association between attention-deficit hyperactivity disorder (ADHD) in Han Chinese children and Val158Met polymorphism of catechol-O-methyltransferase (COMT) gene caused by the missense mutation of G158A in exon 4.</p><p><b>METHODS</b>By using polymerase chain reaction-restriction fragment length polymorphisms the Val158Met polymorphism of COMT gene was tested in 117 children with the diagnosis of ADHD as defined by DSM-IV and in 105 healthy controls living in Shanghai.</p><p><b>RESULTS</b>The frequencies of A allele were 25.21% and 23.81% in the ADHD group and the health controls respectively, which showed no significant difference between the two groups (Chi2=0.5197, P>0.05). There was also no significant difference in the distribution of all genotypes of COMT gene between the ADHD patients and the controls (P>0.05).</p><p><b>CONCLUSION</b>It was suggested that for the Han Chinese children with ADHD in this study, there was no association between ADHD and Val158Met polymorphism of COMT gene.</p>