A survey in relationship between DRD4 genes' EX3 VNTR and rs3758653 polymorphisms to the dose of Methylphenidate in responder children with Attention Deficit Hyperactivity Disorder(ADHD)

Abstract

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common psychiatric disorders starting at an early age with symptoms of attention deficit hyperactivity disorder and impulsivity. Our aim in this study is to investigate the molecular alterations of the DRD4 gene that have been linked to ADHD in previous studies with respect to the dose of methylphenidate. This study and other studies will help us to determine, in the not too distant future, molecular analysis of the DRD4 gene in patients to determine the dose of methylphenidate without having to consult a physician for dose adjustment or experience side effects of the drug.

Materials and Methods: After diagnosis of symptoms severity was assessed using Conners scale. Then, 4 ml of blood was collected in EDTA tubes from each individual and DNA was extracted using Salting out method. After PCR, the products were separated using specific restriction enzymes and then analyzed by gel electrophoresis on 2% agarose polymorphisms of Ex3 VNTR and rs3758653 of DRD4 gene. The last dose to achieve the therapeutic response was recorded in mg / kg. Then, the relationship between the dose of drug used to achieve the therapeutic response, the existence of the mentioned polymorphisms was investigated.

Results: The mean scores of all four domains showed a statistically significant decrease in the mean scores after 4 weeks of treatment compared to the mean scores of pre-treatments. Comparison of the above four areas showed a statistically significant decrease in all areas 8 weeks after treatment compared to pre-treatment.