miRNAs As Biomarkers for Neurodegenerative Diseases

microRNAs (miRNAs) are small noncoding RNAs that regulate mRNA stability and/or protein biosynthesis and, therefore, gene expression. They have been studied and linked to different neurodegenerative disorders. In this chapter, we review miRNAs with strong potential as biomarkers for neurodegenerative disease. We analyzed the available studies on neurodegenerative diseases that report miRNA alterations, considered the reproducibility of the results, and limited the report to studies that analyzed miRNAs in human body fluids of easy access (blood, CSF). Nevertheless, occasionally, we chose to mention miRNAs, which although not analyzed in readily accessible human body fluids, have shown significant dysregulation in human brain and eye tissues. Of the studies consulted for this work, only a few have used large-scale methods such as NGS. In general, real-time PCR has been used to analyze miRNA expression levels. Therefore, we have employed the guidelines for “minimum information for publication of quantitative real-time PCR experiments” (MIQE guidelines) to evaluate the different studies.