Polymorphism of dopamine transporter gene 3'-UTR VNTR in Iranian Azeri Turkish patients with ADHD

Attention Deficit Hyperactivity Disorder (ADHD) is the most common neurobehavioral disorder among children, which several studies have indicated the role of genetic factors in its development. Dopamine transporter gene (DAT1) is one of the candidate genes and a 40-bp variable number of tandem repeat (VNTR) in 3'-UTR of the gene is reported to have a role in ADHD. Here we examined the association between DAT1 VNTR and ADHD susceptibility among Iranian Azeri Turkish children.
The study included 202 patients and 143 controls aged 6-12 years. ADHD children were diagnosed according to DSM-IV and "conners scale" and DAT1 3'-UTR VNTR was genotyped by PCR technique.
The genotypes and allelic distribution of the DAT1 3'-UTR VNTR were not significantly different between the case and control groups (p>0.05) but a significant difference was found in allelic frequencies when the analysis was confined to females (p=0.029).
Our results do not support the role of 10 or 9-repeat alleles as risk alleles in the studied subjects but an association was found between 11-repeat allele and the susceptibility to ADHD in females.