IL-6 and DRD2 Genesare Associated with Hyperkinetic Disorder

Overview

TaqI A polymorphism of the dopamine receptor D2 gene (DRD2) was previously associated withADHD, alcoholism, drug dependence etc., while -174 polymorphism of interleukin-6 (IL-6) gene wasassociated with alcoholism. In our association study, we studied the difference in genotype andallelic frequencies of the above mentioned polymorphisms between boys with ADHD and boys incontrol group. Buccal tissue was used for isolation of genomic DNA using commercial kit UltraCleanTissue DNA (MoBio, USA). PCR with subsequent restriction analysis was used for determination ofgenotypes. Genotype and allelic frequency of TaqI A polymorphism of DRD2 gene was statisticallydifferent between ADHD group and control group (P < 0.04 and P < 0.002, respectively), as well asgenotype and allelic frequency of -174 polymorphism of IL-6 was statistically different betweenstudied groups of boys (P < 0.004 and P < 0.001, respectively). Our study confi rmed the associationfound previously between TaqI A polymorphism and ADHD and provided new data about the fi rstdiscovered association between -174 polymorphism of IL-6 gene and ADHD.

Key words:
ADHD, IL-6, DRD2, association study, polymorphism.