Abstract
Myasthenia gravis (MG) is an autoimmune disease caused by antibodies which attack receptors at the neuromuscular junction. One of the main difficulties in predicting the clinical course of MG is the heterogeneity of the disease, where disease progression differs greatly depending on the subgroup that the patient is classified into. MG subgroups are classified according to: age of onset [early-onset MG (EOMG; onset ≤ 50 years) versus late-onset MG (LOMG; onset > 50 years]; the presence of a thymoma (thymoma-associated MG); antibody subtype [acetylcholine receptor antibody seropositive (AChR+) and muscle-specific tyrosine kinase antibody seropositive (MuSK+)]; as well as clinical subtypes (ocular versus generalized MG). The diagnostic tests for MG, such as antibody titers, neurophysiological tests, and objective clinical fatigue score, do not necessarily reflect disease progression. Hence, there is a great need for reliable objective biomarkers in MG to follow the disease course as well as the individualized response to therapy toward personalized medicine. In this regard, circulating microRNAs (miRNAs) have emerged as promising potential biomarkers due to their accessibility in body fluids and unique profiles in different diseases, including autoimmune disorders. Several studies on circulating miRNAs in MG subtypes have revealed specific miRNA profiles in patients’ sera. In generalized AChR+ EOMG, miR-150-5p and miR-21-5p are the most elevated miRNAs, with lower levels observed upon treatment with immunosuppression and thymectomy. In AChR+ generalized LOMG, the miR-150-5p, miR-21-5p, and miR-30e-5p levels are elevated and decrease in accordance with the clinical response after immunosuppression. In ocular MG, higher levels of miR-30e-5p discriminate patients who will later generalize from those remaining ocular. In contrast, in MuSK+ MG, the levels of the let-7 miRNA family members are elevated. Studies of circulating miRNA profiles in Lrp4 or agrin antibody-seropositive MG are still lacking. This review summarizes the present knowledge of circulating miRNAs in different subgroups of MG.
Highlights
INTRACELLULAR MICRORNASMyasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder with a prevalence of approximately 40–180 per million [1, 2]
Since the aforementioned miRNA study in LOMG [56] revealed lower levels of some miRNAs in patients with OMG compared to GMG, a recent study aimed at determining whether circulating miRNAs could be used as potential predictors of disease generalization in MICRORNASMyasthenia gravis (MG) [61]
The results from this study suggest that increased serum levels of miR-150-5p, which were detected in this study, result from the released miR-150 from activated peripheral CD4+ T cells [79]
Summary
Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder with a prevalence of approximately 40–180 per million [1, 2]. The major described MG subgroups include: age of onset [early-onset MG (EOMG; onset ≤ 50 years) versus late-onset MG (LOMG; onset > 50 years]; the presence of a thymoma (thymoma-associated MG, TAMG); and antibody subtype [acetylcholine receptor antibody-seropositive (AChR+) versus muscle-specific tyrosine kinase antibody seropositive (MuSK+)] [1]. Antibodies to AChR, MuSK, Lrp, or agrin have a useful role as diagnostic biomarkers for the confirmation of MG and classifying the disease subgroup. Their titer does not necessarily correlate with the disease severity or response to treatment [11]. Alterations in miRNA expression and RISC incorporation are dysregulated in many disorders, including cancer and cardiovascular and autoimmune diseases [24,25,26]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
