2026-07-30 | Safety, Tolerability, Pharmacokinetics, Food Effect of Ribitol, and Its Effect on QTcF in Healthy Adults: First-in-Human, Randomized, Double-Blind (Sponsor Unblinded), Placebo-Controlled Studies.
Limb-girdle muscle dystrophy Type R9 (LGMDR9), also known as LGMD Type 2I, is a rare genetic disease caused by partial loss of function of fukutin-related protein (FKRP) enzyme which glycosylates alpha-dystroglycan, thereby stabilizing myocytes during contraction. Hypoglycosylation leads to progressive muscle injury and impaired function including loss of ambulation. Ribitol is an endogenous pentose alcohol and precursor to CDP-ribitol, the substrate of FKRP. This first-in-human study demonstrated that ribitol was well tolerated when administered as single or multiple oral doses over 6 days to healthy adults. PK demonstrated dose-proportional increases in exposure from 0.5 to 15 g (therapeutic dose 9 and 12 g BID for patients weighing >30 to ≤50 kg and >50 kg, respectively); t½ was 9-13 h. A high-fat meal did not affect overall oral bioavailability; indicating ribitol may be taken without regard to food intake. A dedicated QT study using ribitol 21 g revealed no concentration-dependent QTcF prolongation and clinically significant QTcF prolongation was excluded over the entire range of exposures in the study, up to 351.9 µg/mL. Assay sensitivity was demonstrated with the expected effect of moxifloxacin. These results support further development of ribitol for the treatment of LGMDR9.
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2026-07-16 | Limb-girdle Muscular Dystrophy Type 2I/R9: Future Gene Therapy Options of an Extremely Rare Fukutin Protein-related Dystroglycanopathy
Limb-girdle muscular dystrophy type 2I, now designated R9 (LGMD2I/R9), is an autosomal recessive dystroglycanopathy caused by biallelic pathogenic variants in the fukutin-related protein (FKRP) gene. Loss of FKRP glycosyltransferase activity disrupts the ribitol-phosphate-mediated glycosylation of alpha-dystroglycan, reducing matriglycan formation and weakening the link between the sarcolemma and the extracellular matrix. The resulting phenotype ranges from mild, adult-onset limb-girdle weakness to a severe congenital muscular dystrophy, and frequently includes dilated cardiomyopathy and restrictive respiratory failure. No disease-modifying treatment is currently licensed, and management remains supportive. Over the past decade, three broad experimental strategies have moved toward clinical evaluation: adeno-associated virus (AAV)-mediated gene replacement, small-molecule substrate supplementation with ribitol, and combinatorial approaches that pair gene replacement with muscle-anabolic transgenes such as follistatin. Registered early-phase AAV-FKRP programmes and the placebo-controlled FORTIFY trial of oral ribitol provide important translational context, but peer-reviewed clinical efficacy and long-term safety data remain limited; interim registry, conference and sponsor-reported findings should therefore be interpreted cautiously. This narrative review synthesises the molecular pathophysiology of FKRP-related dystroglycanopathy, appraises the natural history and outcome measures relevant to trial design, and critically evaluates the preclinical and early clinical evidence for gene-based and substrate-based therapies. It concludes with a discussion of unresolved translational barriers and a forward-looking assessment of the therapeutic pipeline for this ultra-rare neuromuscular disorder.
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2026-07-14 | PPMO therapy for dysferlinopathy induces pseudoexon skipping and restoration of functional protein.
The dysferlinopathies are a spectrum of autosomal recessive muscle diseases caused by mutations in the dysferlin gene (DYSF) gene. Clinical manifestations vary from asymptomatic hyperCKemia to severe muscle pathology and loss of muscle function. These are designated limb-girdle muscular dystrophy type 2R or LGMDR2 (formerly LGMD2B or Miyoshi myopathy). Among other functions, dysferlin is crucial for plasma membrane repair and maintenance of intracellular calcium homeostasis. In previous studies, we identified in two independent point mutations deep within introns that cause aberrant DYSF mRNA splicing and the inclusion of pseudoexons within transcripts that disrupt protein expression. In this study, we generated and characterized a novel mouse model for one of these mutations (within DYSF intron 44). In these mice, a segment of human DYSF DNA containing the mutant intronic sequence flanked by surrounding human exon sequences replaces the normal homologous mouse DNA. These mice exhibit aberrant Dysf pre-mRNA splicing, pseudoexon inclusion, loss of DYSF protein expression, and muscle pathology similar to that observed in patients. Using this new model, we identified antisense oligonucleotides and then a PPMO that blocks the mouse Dysf pre-mRNA splicing complexes from binding the mutant pre-mRNA, thereby restoring nearly normal muscle histology and function.
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2026-06-21 | Consistent MYORG and STRADB Downregulation in DMD and LGMD: Rationale for Deoxygalactonojirimycin Repurposing in Dystrophic and Aging Muscle
Abstract Background MYORG (myogenesis-regulating glycosidase) and STRADB (STE20-related kinase adapter protein beta) were previously identified as activity-mediated skeletal muscle genes with potential roles in frailty and sarcopenia. We hypothesized that, if these genes are sustained by neuromuscular contractile activity, their expression should be consistently downregulated in muscular dystrophies, conditions defined by progressive muscle degeneration and secondary functional disuse. Methods We performed a systematic cross-dataset transcriptomic analysis of five publicly available GEO microarray datasets of human skeletal muscle. Discovery analysis was conducted in GSE3307 (Affymetrix HG-U133A/B; samples spanning DMD, LGMD2A/B/I, BMD, FSHD, JDM, ALS, AQM versus healthy controls). Independent external validation was performed in GSE38417 (HG-U133 Plus 2.0, DMD; n=16/6), GSE11681 (HG-U133A/B, LGMD2A; n=8-10/9-10), GSE465 (HG-U95Av2/B/C, multi-disease), and GSE1007 (HG-U95B/C/E, DMD; n=10-11/11). Raw CEL files underwent array-level quality assessment using NUSE and RLE diagnostics prior to normalization. Seven poor-quality arrays were excluded (none from Control, DMD, or LGMD groups). Remaining arrays were processed by robust multi-array average (RMA) normalization, and differential expression was assessed by limma with Benjamini-Hochberg FDR correction. Results MYORG was significantly downregulated in DMD (log2 fold-change [logFC] = -0.93, adj.P<0.001), LGMD2A (logFC = -0.82, adj.P<0.01), LGMD2B (logFC = -1.01, adj.P<0.01), and LGMD2I (logFC = -1.03, adj.P<0.01) in GSE3307. STRADB was significantly reduced in DMD (logFC = -0.33, adj.P<0.05) and showed a near-significant trend in LGMD2I (logFC = - 0.42, adj.P = 0.061). MYORG downregulation in DMD was independently replicated in GSE38417 (logFC = -1.40, adj.P<0.001) and GSE1007 (logFC = -0.80, adj.P<0.001). STRADB was also significantly downregulated in GSE38417 DMD (logFC = -0.45, adj.P<0.001). Deoxygalactonojirimycin, an iminosugar and an FDA/EMA-approved pharmacological chaperone (migalastat/Galafold) for Fabry disease, has been reported to be a specific molecular interactor that stabilizes MYORG protein in skeletal muscle. Conclusions This multi-dataset study further supports the role of MYORG and STRADB as activity-sensitive muscle genes that are robustly downregulated in DMD and LGMD. The pharmacological interaction between migalastat and MYORG provides a mechanistically grounded rationale for investigating this approved agent as an adjunct therapy in muscular dystrophies, in combination with the existing standard of care. This also supports active investigation of iminosugar analogs to target MYORG as potential therapeutics for improving skeletal muscle function in dystrophies, frailty, and sarcopenia.
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2026-06-18 | Clinical presentations and pathophysiological mechanisms of dystroglycanopathy: advancing therapeutic strategies.
Dystroglycanopathies are muscular dystrophies with varying clinical severities, ranging from congenital-onset to adult limb-girdle muscular dystrophy. Dystroglycanopathies are caused by a loss of function of the extracellular matrix receptor α-dystroglycan, a widely expressed cell-surface glycoprotein required for the formation and function of various muscle and non-muscle tissues. In severe clinical presentations, individuals with dystroglycanopathy experience, in addition to muscle weakness and cardiac involvement, structural ocular and CNS malformations, leading to intellectual disability and epilepsy. Currently, management is only symptomatic. Advances in the understanding of the pathophysiology and genetics have identified new therapeutic targets. Emerging therapeutic approaches, including adeno-associated virus gene therapy for limb-girdle muscular dystrophy associated with pathogenic variants in FKRP (the most common form of dystroglycanopathy) and ribitol-based therapies, are being evaluated in clinical trials and could expand treatment options.
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