miR-146A and miR-146B Promoter Methylation and Common Sequence Variations Are Not Likely to Be Involved in Autism Spectrum Disorder.

One of the well-studied epigenetic regulators is miRNA (miRNA) which plays critical roles in gene regulation and has been implicated in autism spectrum disorder (ASD) pathology, particularly through their involvement in neuroinflammation and neuronal regulation. MiR-146A and miR-146B are of special interest due to their dysregulation in ASD. Epigenetic modifications, such as promoter methylation, and genetic variations in miRNAs can influence their expression and function, yet their roles in ASD remain unclear. This study aimed to investigate promoter methylation patterns and sequence variations in miR-146A and miR-146B to evaluate their potential contributions to ASD. The study included Egyptian patients with ASD (ages 5-16 years) diagnosed using DSM-V criteria and assessed for severity using the Childhood Autism Rating Scale (CARS). DNA was extracted from peripheral blood samples of 93 autistic patients and 44 age-matched controls. Methylation-specific PCR (MSP) was used to analyze promoter methylation of miR-146A and miR-146B, while Sanger sequencing was employed to detect sequence variations in these genes and their flanking regions. Statistical analyses included independent t-tests, ANOVA, ROC curve, and Pearson correlation. No significant differences in promoter methylation levels of miR-146A and miR-146B were observed between ASD cases and controls or among severity subgroups (P > 0.05). Sequence variation analysis identified no significant differences in the distribution of common SNPs (rs2910164 and rs2224374). However, a novel miR-146A upstream variant (C/A at 5:160,485,254) was discovered in one case with autism. Methylation and common genetic variations in miR-146A and miR-146B are unlikely to play significant roles in ASD in this population. The discovery of a novel upstream variant highlights the potential importance of regulatory regions in miRNA function. Further studies with larger cohorts and functional validation are recommended.