Dysregulation of miRNAs in Sicilian Patients with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is considered a neurodevelopmental disorder and the pathogenic mechanisms responsible are still unknown, but it is believed to have a rather heterogeneous etiology involving both non-genetic and genetic factors. In this study, we performed a systematic analysis of miRNAs and functional analysis of pathways, to ex-plore their possible roles and/or mechanisms involved in pathology, as well as their pos-sible role as prenatal and/or postnatal, prognostic, and diagnostic biomarkers. We performed analyses on peripheral blood mononuclear cells from 12 Sicilian patients with ASD and 15 healthy controls and subjected them to small RNA sequencing. Differen-tial expression analysis was performed using DESeq2 (version 1.44.0), with significance defined as |fold change| ≥ 1.5 and adjusted p ≤ 0.05. Ingenuity Pathway Analysis (IPA) was applied to evaluate functional enrichment, focusing Diseases and Bio-Functions. A total of 998 miRNAs were identified as differentially expressed in patients with ASD (424 upregulated and 553 downregulated). IPA revealed enrichment in pathways re-lated to psychological and neurological diseases. IPA network analysis of differentially expressed miRNAs and their predicted targets identified multiple enriched interaction networks; we focused on three networks related to inflammation, cell survival and mech-anotransduction, synaptic plasticity, and neuronal excitability. We identified four miR-NAs: miR-296-3p, miR-27a, miR-146a-5p, and miR-29b-3p. The variance shown in the principal component analysis suggests that most miR-RNAs are expressed very differently in ASD compared to normal individuals. This preliminary study high-lighted and confirmed that inflammatory, autoimmune, and infectious mechanisms play a decisive role in ASD, emphasizing the specific function of miRNAs that regulate S100 family genes, neuronal migration, and the creation of communication systems.