Association between polymorphisms of the DBH and DAT1 genes and attention deficit hyperactivity disorder in children from Jordan.

Attention deficit hyperactivity disorder (ADHD) is one of the most common neuropsychiatric disorders in children. In this study, the association between 10-repeats in the DAT1 gene and the (GT)n repeat in the DBH gene and ADHD was examined in children from Jordan. In addition, the levels of dopamine-β-hydroxylase enzyme activity in the plasma of ADHD children were evaluated. Fifty children with ADHD and 50 age- and gender-matched control subjects were recruited. The results showed significant differences between the ADHD group and controls with respect to the plasma levels of dopamine-β-hydroxylase enzyme activity (25.4±2.3 vs. 84.7±5.0 μmol/min; p<0.01). Moreover, the 10-repeat DAT1 gene and (GT)n DBH gene polymorphisms were significantly associated with ADHD development (p<0.05). In conclusion, the DBH and DAT1 genes appear to play a role in the development of ADHD in the Jordanian population.