RESUMEN
<p><b>OBJECTIVE</b>To analyse the association between polymorphism in human synaptosomal-associated protein of 25 000 (SNAP-25) gene and attention deficit hyperactivity disorder (ADHD) in Han Chinese children.</p><p><b>METHODS</b>The study samples were comprised of 100 integrated ADHD trios (included proband and biological parents) and 97 unrelated controls. Association of polymorphism with ADHD and its subtype was examined by: (1) comparing cases and controls; (2) using family-based association study in transmission disequilibrium test (TDT).</p><p><b>RESULTS</b>Case-control analysis of short tandem repeat (STR) showed that there was no significant difference between the two groups in allele gene frequency and genotype frequency (P > 0.05); TDT analysis of the rs363006 SNP and the rs362549 SNP revealed no association between SNAP-25 polymorphisms and ADHD (P > 0.05). But after a stratification by ADHD subtype, the rs362549 SNP A allele showed a tendency to preferentially transmitted to ADHD-I subtype (chi(2) = 8.00, P < 0.01); and the rs362549 SNP G allele had a tendency to preferentially transmitted to ADHD-C subtype (chi(2) = 4.122, P < 0.05).</p><p><b>CONCLUSIONS</b>No association was found between SNAP-25 polymorphisms and ADHD. There was a possible association between rs362549 SNP polymorphism and ADHD subtypes, but the findings require replication before drawing a definitive conclusion.</p>