Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia. However, biomarkers that require testing in the brain tissue pose a formidable practical barrier to AD diagnostic innovation. MicroRNAs (miRNAs) are responsible for control of gene expression at the posttranscriptional level and are essential for the function of neuronal networks and neuronal survival. miRNA expression can impact the regulation of APP (amyloid beta A4 precursor protein), PSEN1 (presenilin 1), PSEN2 (presenilin 2), and BACE1 (beta-secretase 1) genes in the brain that were previously implicated in AD pathophysiology. Little is known, however, on the extent to which peripheral tissue (e.g., whole blood) miRNA variation might offer clinical predictive value for AD. Moreover, few studies have examined multiple peripheral miRNA expression data at the same time. We report here, to the best of our knowledge, the first whole-blood-based and parallel study of seven miRNAs ( hsa-miR-9-5p , hsa-miR-29a-3p , hsa-miR-106a-5p , hsa-miR-106b-5p , hsa-miR-107 , hsa-miR-125a-3p , and hsa-miR-125b-5p ) in relation to AD susceptibility. Notably, these miRNAs are situated “upstream” to the genes implicated in AD. We measured the whole-blood miRNA expression by a real-time polymerase chain reaction in a large study sample ( n = 281), comprising patients with AD ( n = 172) and healthy controls ( n = 109). A reduction in whole-blood expression of hsa-miR-9-5p , hsa-miR-106a-5p , hsa-miR-106b-5p , and hsa-miR-107 was significantly associated with an increased risk of AD ( p < 0.05). Notably, after receiver operating characteristics curve analyses, hsa-miR-106a-5p displayed, as a predictor variable, 93% specificity and 68% sensitivity. On the other hand, the expression of hsa-miR-29a-3p , hsa-miR-125a-3p , and hsa-miR-125b-5p was not significantly different between patients and controls ( p > 0.05). In conclusion, these observations warrant replication in larger samples while making a contribution to translational research, precision medicine, and biomarker literatures, by expanding the current efforts for AD diagnostic innovation to the realm of epigenomic pathways such as miRNA expression variation among patients.

Parkinson's disease (PD) is a frequently occurring neurodegenerative motor disorder adversely impacting global health. There is a paucity of biomarkers and diagnostics that can forecast susceptibility to PD. A new research frontier for PD pathophysiology is the study of variations in microRNA (miRNA) expression whereby miRNAs serve as “upstream regulators” of gene expression in relation to functioning of the dopamine neuronal pathways. Leucine-Rich Repeat Kinase 2 ( LRRK2 ) is a frequently studied gene in PD. Little is known about the ways in which expression of miRNAs targeting LRKK2 impact PD susceptibility. In a sample of 204 unrelated subjects (102 persons with PD and 102 healthy controls), we report here candidate miRNA expression in whole blood samples as measured by real-time PCR ( hsa-miR-4671-3p, hsa-miR-335-3p, hsa-miR-561-3p, hsa-miR-579-3p, and hsa-miR-3143 ) that target LRRK2 . Using step-wise logistic regression, and controlling for covariates such as age, gender, PD disease severity, concomitant medications, and co-morbidity, we found that the combination of has-miR-335-3p, has-miR-561-3p, and has-miR-579-3p account for 50% of the variation in regards to PD susceptibility ( p < 0.0001). Notably, the hsa-miR-561-3p expression was the most robust predictor of PD in both univariate and multivariate analyses ( p < 0.001). Moreover, the biological direction (polarity) of the association was plausible in that the candidate miRNAs displayed a diminished expression in patients. This is consistent with the hypothesis that decreased levels of miRNAs targeting LRRK2 might result in a gain of function for LRRK2, and by extension, loss of neuronal viability. To the best of our knowledge, this is the first clinical association study of the above candidate miRNAs' expression in PD using peripheral samples. These observations may guide future clinical diagnostics research on PD.

Alzheimer disease (AD) is a common complex neurodegenerative disorder accounting for nearly 50% to 70% of dementias worldwide. Yet the current diagnostic options for AD are limited. New diagnostic innovation strategies focusing on novel molecules and pathways are sorely needed. In this connection, microRNAs (miRNAs) are conserved small noncoding RNAs that regulate posttranscriptional gene expression and are vital for neuronal development and its functional sustainability. Conceivably, biological pathways responsible for the biogenesis of miRNAs represent a veritable set of upstream candidate genes that can be potentially associated with the AD pathophysiology. Notably, whereas functional single-nucleotide polymorphisms (SNPs) in miRNA biogenesis pathway genes have been studied in other complex diseases, surprisingly, virtually no such study has been conducted on their relevance in AD. Moreover, novel diagnostics identified in easily accessible peripheral tissues such as the whole blood samples represent the initial entry or gateway points on the biomarker discovery critical path for AD. To the best of our knowledge, we report here the first association study of functional SNPs, as measured by real-time PCR in 10 “upstream” candidate genes critically situated on the miRNA biogenesis pathway, in a large sample of AD patients (N=172) and healthy controls (N=109) in a hitherto understudied world population from the Mersin region of the Eastern Mediterranean. We observed a significant association between 2 candidate genes and AD, TARBP2 rs784567 genotype and AD (χ²=6.292, P=0.043), and a trend for RNASEN rs10719 genotype (χ²=4.528, P=0.104) and allele (P=0.035). Functional SNP variations in the other 8 candidate genes (DGCR8, XPO5, RAN, DICER1, AGO1, AGO2, GEMIN3, and GEMIN4) did not associate with AD in our sample. Given the putative biological importance of miRNA biogenesis pathways, these emerging data can provide a new foundation to stimulate future debate and genetic investigations of AD, focusing on new molecular mechanisms such as miRNA biogenesis, particularly in accessible peripheral tissues for novel molecular diagnostics for dementia.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) characterized by demyelination and axonal degeneration. Abnormal expression of microRNAs (miRNAs) plays an important role in MS pathology. In this cohort study, differential expression of the four miRNAs ( hsa-miR-155-5p, hsa-miR-9-5p, hsa-miR-181a-5p, and hsa-miR-125b-5p) was investigated in 69 individuals, including 39 MS patients (relapsing-remitting MS (RRMS), n = 27; secondary progressive MS (SPMS), n = 12) and 30 healthy controls. In silico analyses revealed possible genes and pathways specific to miRNAs. Peripheral blood miRNA expressions were detected by quantitative real-time PCR (qPCR). hsa-miR-181a-5p was downregulated and associated with increased MS risk ( P = 0.012). The other three miRNAs were upregulated and not associated with MS ( P < 0.05). The area under the curve (AUC) is 0.779. In silico analyses showed that hsa-miR-181a-5p may participate in MS pathology by targeting MAP2K1, CREB1, ATXN1, and ATXN3 genes in inflammation and neurodegeneration pathways. The circulatory hsa-miR-181a-5p can regulate target genes, reversing the mechanisms involved in MS pathologies such as protein uptake and processing, cell proliferation and survival, inflammation, and neurodegeneration. Thus, this miRNA could be used as an epigenomic-guided diagnostic tool and for therapeutic purpose.

Genome editing technologies include techniques used for desired genetic modifications and allow the insertion, modification or deletion of specific DNA fragments. Recent advances in genome biology offer unprecedented promise for interdisciplinary collaboration and applications in gene editing. New genome editing technologies enable specific and efficient genome modifications. The sources that inspire these modifications and already exist in the genome are DNA degradation enzymes and DNA repair pathways. Six of these recent technologies are the clustered regularly interspaced short palindromic repeats (CRISPR), leveraging endogenous ADAR for programmable editing of RNA (LEAPER), recruiting endogenous ADAR to specific transcripts for oligonucleotide-mediated RNA editing (RESTORE), chemistry-based artificial restriction DNA cutter (ARCUT), single homology arm donor mediated intron-targeting integration (SATI), RNA editing for specific C-to-U exchange (RESCUE). These technologies are widely used from various biomedical researches to clinics, agriculture, and allow you to rearrange genomic sequences, create cell lines and animal models to solve human diseases. This review emphasizes the characteristics, superiority, limitations, also whether each technology can be used in different biological systems and the potential application of these systems in the treatment of several human diseases.