Molecular evaluation of Ex3 VNTR polymorphism of the DRD4 gene in patients with autism spectrum disorder

Abstract Objective Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders that affect social and communication skills. They are characterized by severe communication and social skills disabilities and limited and repetitive activities and their prevalence appear to be steadily increasing. Genes involved in the dopamine pathway may play an important role in the development of autism and this study we evaluated the possible association between Ex3 VNTR polymorphism of the DRD4 gene and autism spectrum disorder in the Iranian population. Materials & Methods In this case-control study,97 children with autism and 103 healthy individuals were selected from the northwestern area of Iran as the case group and the control group, respectively. After genomic extraction from peripheral blood samples by the proteinase K method, the polymerase chain reaction (PCR) technique was used to determine the genotypes of polymorphism. The data then were coded and analyzed using SPSS22 software. Result The results of the study showed that the allele frequencies were different in the two groups and some of these differences were statistically significant. The most common allele in both the ASD and the control group was the 700 bp allele and its frequency was significantly different in the two groups, being more common in the ASD group. (p-value=0.0018). The other allele with a statistically different frequency was the 800 bp allele which was less frequent in the ASD group (p-value=0.0017). Conclusion These results suggest a potential association between Ex3 VNTR polymorphism of the DRD4 gene and autism spectrum disorder in the Iranian population and necessitate further studies evaluating the DRD4 gene