This research investigates the alleles of Variable Number of Tandem Repeats (VNTR) intron 8 of the gene SLC6A3 with attention-deficit / hyperactivity disorder (ADHD) in children and adolescents. The study’s target population consisted of children and adolescents referred to the specialized clinic, as well as students attending school in Rasht city during 2021-2022. A sample of 95 children between the ages of 6 and 10 with ADHD was selected as the ADHD group, and 95 healthy children were selected as the control group using purposive sampling. The subjects completed the Child Symptom Inventory-4 (CSI-4) checklist after a clinical interview, and demographic information was collected. Genetic sampling was carried out through hair follicles. The sequence of interest was proliferated using the Polymerase Chain Reaction technique )PCR(; afterward, the samples were used for genotype identification on polyacrylamide gel electrophoresis. The chi-square test results indicated that the 5R / 5R genotype (P = 0.026, χ2 = 7.26) and the 5R allele (P = 0.002, χ2 = 9.35) had a higher frequency compared to the control group. Additionally, the odds ratio test indicated that, compared to other genotypes and alleles, the 5R / 5R genotype (OR = 2.75, 95% CI = 1.29-5.82, P = 0.01) and the 5R allele (OR = 2.02, 95% CI = 1.28-3.19, P = 0.002) increase the odds of developing ADHD by 2.7 and 2 times higher, respectively. The present study successfully showed the association between intron 8 gene polymorphism, which is responsible for encoding the dopamine transporter as well as ADHD in children and adolescents in Iran.
Copyright © 2024 Tehran University of Medical Sciences. Published by Tehran University of Medical Sciences.