###### Abstract  
MicroRNAs (miRNAsAs), a class of non-coding RNAs, seem to play a key role in complex diseases like multiple sclerosis (MS), as well as in many cognitive functions associated with the disease. In a previous cross-sectional evaluation on pediatric MS (PedMS) patients, the expression of some miRNAs and their target genes were found to be associated with the scores of some neuropsychiatric tests, thus suggesting that they may be involved in early processes of cognitive impairment. To verify these data, we asked the same patients to be re-evaluated after a 1-year interval; unfortunately, only nine of them agreed to this further clinical and molecular analysis. The main results showed that 13 differentially expressed miRNAs discriminated the two time-points. Among them, the expression of miR-182-5p, miR-320a-3p, miR-744-5p and miR-192-5p significantly correlated with the attention and information processing speed performances, whereas the expression of miR-182-5p, miR-451a, miR-4742-3p and miR-320a-3p correlated with the expressive language performances. The analysis of mRNA expression uncovered 58 predicted and/or validated miRNA-target pairs, including 23 target genes, some of them already associated with cognitive impairment, such as the transducing beta like 1 X-linked receptor-1 gene (_TBLXR1_), correlated to disorders of neurodevelopment; the Snf2 related CREBBP activator protein gene (_SRCAP_) that was found implicated in a rare form of dementia; and the glia maturation factor beta gene (_GMFB_), which has been reported to be implicated in neurodegeneration and neuroinflammation. No molecular pathways involving the most targeted genes survived the adjustment for multiple data. Although preliminary, these findings showed the feasibility of the methods also applied to longitudinal investigations, as well as the reliability of the obtained results. These findings should be confirmed in larger PedMS cohorts in order to identify early markers of cognitive impairment, towards which more efficient therapeutic efforts can be addressed.  
pediatric multiple sclerosis; microRNA; gene target; high-throughput next-generation sequencing +
Footnote †: journal: Applied Soft  
e-print 2020-0001-0001-0001-0001-0001-0001-0001-0001-0001-  
elusive due to the multifactorial nature of MS, which involves environmental factors, several genes and their epigenetic interactions [2]. Lately, the evidence that up to 5% of patients with MS experience their first clinical symptoms/signs before the age of 18 years [3] has offered the opportunity to investigate the very early steps of this heterogeneous disease, also helping to disentangle the complex molecular scenario of the latest phases and possibly leading to more targeted therapeutic efforts. To this aim, integrated approaches using deep sequencing technologies of next-generation sequencing (HT-NGS) provide valuable support, e.g., to assess the differential expression of microRNAs (miRNAs), which are epigenetic factors, the functions of which have been associated with MS and its phenotypic features [4].  
Following these suggestions, in a previous study performed on a selected group of 19 pediatric MS (PedMS), 12 upregulated and 1 downregulated miRNAs resulted, compared to 20 age-matched controls [5]; six miRNAs were confirmed in an adult MS population (\(n=58\) patients versus \(n=20\) controls) suggesting that they may be considered as distinctive markers of the disease independently of their age [6]. It is also worth noting that the expression of 11 miRNAs correlated with the scores obtained in different cognitive tests; although none of them passed the 0.05 threshold of statistical significance, they seemed to point in the direction of a possible impact of miRNAs in PedMS cognitive performance [7].  
To verify these findings, we asked the same PedMS population to be re-evaluated after 1-year by following the same clinical, neuropsychological and molecular protocols.