Tiny molecules, mighty impacts: MicroRNAs in muscular dystrophies and myopathies

Microribonucleic acids (miRNAs) are small non-coding RNA molecules that regulate gene expression post-transcriptionally and play essential roles in muscle differentiation, regeneration, and metabolism. A specific subset, known as myomiRs, is predominantly expressed in muscle tissue and has been implicated in key molecular pathways underlying muscular dystrophies and myopathies. Due to their stability in biological fluids, myomiRs have emerged as non-invasive biomarkers. The present narrative review summarizes selected studies addressing myomiR expression patterns, functional roles, and translational implications in muscular dystrophies and myopathies, particularly Duchenne muscular dystrophy (DMD), myotonic dystrophy type 1 (DM1), limb-girdle muscular dystrophy (LGMD), McArdle disease, and myofibrillar myopathy (MFM), highlighting their biological relevance and clinical potential. The available evidence indicates that myomiRs such as miR-1, miR-133a/b, miR-206, miR-29b, miR-31, and miR-486 are differentially expressed across these disorders and are involved in processes including muscle degeneration, regeneration, fibrosis, and inflammation. In DMD, several myomiRs are upregulated, reflecting ongoing muscle damage and regenerative activity, whereas in DM1, downregulation of miR-1, miR-133a/b, and miR-29b contributes to impaired muscle maturation and fibrosis. In contrast, miR-206 appears increased as part of a regenerative response, whereas miR-223–3p may reflect inflammatory activity or muscle damage. Evidence for McArdle disease remains scarce, underscoring the need for further investigation. In conclusion, understanding miRNA signatures may facilitate earlier diagnosis, disease stratification, and the development of targeted therapies in muscular dystrophies and myopathies.