RARE DISEASE
Calpain-3-related limb-girdle muscular dystrophy R1
Calpain-3-related limb-girdle muscular dystrophy R1
Calpain-3-related limb-girdle muscular dystrophy R1
Synonyms: Autosomal recessive limb-girdle muscular dystrophy type 2A, Calpain-3-related LGMD R1, LGMD type 2A, LGMD2A, Limb-girdle muscular dystrophy due to calpain deficiency, Limb-girdle muscular dystrophy type 2A, Primary calpainopathy
Synonyms: Autosomal recessive limb-girdle muscular dystrophy type 2A, Calpain-3-related LGMD R1, LGMD type 2A, LGMD2A, Limb-girdle muscular dystrophy due to calpain deficiency, Limb-girdle muscular dystrophy type 2A, Primary calpainopathy
Synonyms: Autosomal recessive limb-girdle muscular dystrophy type 2A, Calpain-3-related LGMD R1, LGMD type 2A, LGMD2A, Limb-girdle muscular dystrophy due to calpain deficiency, Limb-girdle muscular dystrophy type 2A, Primary calpainopathy
Drug discovery
2
drugs
With orphan designations
Overview
Calpain-3-related limb-girdle muscular dystrophy R1 (LGMD2A/R1) is an autosomal recessive disorder caused by CAPN3 mutations, leading to progressive proximal muscle weakness, atrophy, and dystrophic features in skeletal muscle without cardiac involvement. Onset ranges from childhood to adulthood, with hallmark features including waddling gait, scapular winging, and calf pseudohypertrophy. Diagnosis combines genetic testing, elevated serum CK, and muscle biopsy showing calpain-3 deficiency [1][9][14].
Categories: rare genetic diseases, rare neurological diseases
Research Papers
133 drug discovery papers about Calpain-3-related limb-girdle muscular dystrophy R1, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
133 drug discovery papers about Calpain-3-related limb-girdle muscular dystrophy R1, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
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.
2026-03-30 | Inflammation-Linked Muscle Atrophy in Limb Girdle Muscular Dystrophy R1 (LGMDR1): Insights into Disease Mechanisms
Background: Muscle atrophy is a major feature of Limb Girdle Muscular Dystrophy R1 (LGMDR1) patients, but its underlying molecular mechanisms have not been fully explored. While the ubiquitin–proteasome system (UPS) is known to be involved in muscle protein degradation, inflammation commonly observed in LGMDR1 patients may further activate the UPS. This study aimed to explore the role of inflammation in the muscle atrophy of LGMDR1 patients. Methods: Muscle biopsies from six confirmed LGMDR1 patients (with CAPN3 variants and reduced calpain-3 protein expression) were analyzed for atrophy-related markers, MuRF1 and Atrogin-1, using qRT-PCR and Western blotting. The expression of cytokines, TNF-α, IL-1β, and IL-6 was analyzed by qRT-PCR from muscle biopsies and by ELISA from serum samples. The NFκB, FOXO1, and FOXO3 gene expression was analyzed using qRT-PCR and Western blotting from muscle biopsies. Results: Elevated TNF-α levels were associated with increased UPS activity, reflected by upregulated NFκB, FOXO1, MuRF1, and Atrogin-1 expression in LGMDR1. Conclusion: Our findings indicate that increased TNF-α expression is associated with muscle wasting in LGMDR1 patients by targeting UPS pathway mediators that activate ubiquitin ligases—MuRF1 and Atrogin-1. These findings suggest that targeting TNF-α signaling and its downstream factors may help develop therapeutic interventions to prevent muscle atrophy in LGMDR1 patients.
2025-11-27 | Dantrolene‐Responsive Muscle Stiffness in a Patient With a Normal Neurologic Exam and EMG: A Case Report
Muscle stiffness or rigidity is a common problem yet is addressed in few studies. Patients with muscle rigidity/spasticity due to injury of upper motor neurons or genetic muscle diseases are sometimes treated with dantrolene. It is not widely used to treat muscle tightness in patients with a negative workup. Here, we present a 62-year-old neuromuscular physician with no family history of hereditary neuromuscular disease who presented with prolonged, episodic muscle rigidity causing significant functional limitations. Next-generation sequencing identified a heterozygous calpain 3 (CAPN3) variant [NM_000070.3(CAPN3):c.2393C > A (p.Ala798Glu)] categorized as pathogenic for autosomal-recessive CAPN3-related limb girdle muscular dystrophy type 1 (LGMD R1), which is of unclear significance. He was treated with dantrolene and showed marked functional gains that were lost with attempts to wean off medication. This case suggests that there may be a subset of patients suffering from muscle tightness who benefit from dantrolene.
2024-02-22 | A knock down strategy for rapid, generic, and versatile modelling of muscular dystrophies in 3D-tissue-engineered-skeletal muscle
Abstract Background Human iPSC-derived 3D-tissue-engineered-skeletal muscles (3D-TESMs) offer advanced technology for disease modelling. However, due to the inherent genetic heterogeneity among human individuals, it is often difficult to distinguish disease-related readouts from random variability. The generation of genetically matched isogenic controls using gene editing can reduce variability, but the generation of isogenic hiPSC-derived 3D-TESMs can take up to 6 months, thereby reducing throughput. Methods Here, by combining 3D-TESM and shRNA technologies, we developed a disease modelling strategy to induce distinct genetic deficiencies in a single hiPSC-derived myogenic progenitor cell line within 1 week. Results As proof of principle, we recapitulated disease-associated pathology of Duchenne muscular dystrophy and limb-girdle muscular dystrophy type 2A caused by loss of function of DMD and CAPN3, respectively. shRNA-mediated knock down of DMD or CAPN3 induced a loss of contractile function, disruption of tissue architecture, and disease-specific proteomes. Pathology in DMD-deficient 3D-TESMs was partially rescued by a candidate gene therapy treatment using micro-dystrophin, with similar efficacy compared to animal models. Conclusions These results show that isogenic shRNA-based humanized 3D-TESM models provide a fast, cheap, and efficient tool to model muscular dystrophies and are useful for the preclinical evaluation of novel therapies.
2024-02-14 | Engineered mischarged transfer RNAs for correcting pathogenic missense mutations.
Missense mutations account for approximately 50% of pathogenic mutations in human genetic diseases, and most lack effective treatments. Gene therapies, gene editing, and RNA therapies, including transfer RNA (tRNA) modalities, are common strategies for genetic disease treatments. However, reported tRNA therapies are for nonsense mutations only. It has not been explored how tRNAs can be engineered to correct missense mutations. Here, we describe missense-correcting tRNAs (mc-tRNAs) as a potential therapeutic for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs charged with one amino acid, but read codons of another in translation. We first developed a series of fluorescent protein-based reporters that indicate the successful correction of missense mutations via restoration of fluorescence. We engineered mc-tRNAs that effectively corrected serine and arginine missense mutations in the reporters and confirmed the amino acid substitution by mass spectrometry and mc-tRNA expression by sequencing. We examined the transcriptome response to mc-tRNA expression and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an mc-tRNA to rescue a pathogenic CAPN3 Arg-to-Gln mutant involved in LGMD2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
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.
2026-03-30 | Inflammation-Linked Muscle Atrophy in Limb Girdle Muscular Dystrophy R1 (LGMDR1): Insights into Disease Mechanisms
Background: Muscle atrophy is a major feature of Limb Girdle Muscular Dystrophy R1 (LGMDR1) patients, but its underlying molecular mechanisms have not been fully explored. While the ubiquitin–proteasome system (UPS) is known to be involved in muscle protein degradation, inflammation commonly observed in LGMDR1 patients may further activate the UPS. This study aimed to explore the role of inflammation in the muscle atrophy of LGMDR1 patients. Methods: Muscle biopsies from six confirmed LGMDR1 patients (with CAPN3 variants and reduced calpain-3 protein expression) were analyzed for atrophy-related markers, MuRF1 and Atrogin-1, using qRT-PCR and Western blotting. The expression of cytokines, TNF-α, IL-1β, and IL-6 was analyzed by qRT-PCR from muscle biopsies and by ELISA from serum samples. The NFκB, FOXO1, and FOXO3 gene expression was analyzed using qRT-PCR and Western blotting from muscle biopsies. Results: Elevated TNF-α levels were associated with increased UPS activity, reflected by upregulated NFκB, FOXO1, MuRF1, and Atrogin-1 expression in LGMDR1. Conclusion: Our findings indicate that increased TNF-α expression is associated with muscle wasting in LGMDR1 patients by targeting UPS pathway mediators that activate ubiquitin ligases—MuRF1 and Atrogin-1. These findings suggest that targeting TNF-α signaling and its downstream factors may help develop therapeutic interventions to prevent muscle atrophy in LGMDR1 patients.
2025-11-27 | Dantrolene‐Responsive Muscle Stiffness in a Patient With a Normal Neurologic Exam and EMG: A Case Report
Muscle stiffness or rigidity is a common problem yet is addressed in few studies. Patients with muscle rigidity/spasticity due to injury of upper motor neurons or genetic muscle diseases are sometimes treated with dantrolene. It is not widely used to treat muscle tightness in patients with a negative workup. Here, we present a 62-year-old neuromuscular physician with no family history of hereditary neuromuscular disease who presented with prolonged, episodic muscle rigidity causing significant functional limitations. Next-generation sequencing identified a heterozygous calpain 3 (CAPN3) variant [NM_000070.3(CAPN3):c.2393C > A (p.Ala798Glu)] categorized as pathogenic for autosomal-recessive CAPN3-related limb girdle muscular dystrophy type 1 (LGMD R1), which is of unclear significance. He was treated with dantrolene and showed marked functional gains that were lost with attempts to wean off medication. This case suggests that there may be a subset of patients suffering from muscle tightness who benefit from dantrolene.
2024-02-22 | A knock down strategy for rapid, generic, and versatile modelling of muscular dystrophies in 3D-tissue-engineered-skeletal muscle
Abstract Background Human iPSC-derived 3D-tissue-engineered-skeletal muscles (3D-TESMs) offer advanced technology for disease modelling. However, due to the inherent genetic heterogeneity among human individuals, it is often difficult to distinguish disease-related readouts from random variability. The generation of genetically matched isogenic controls using gene editing can reduce variability, but the generation of isogenic hiPSC-derived 3D-TESMs can take up to 6 months, thereby reducing throughput. Methods Here, by combining 3D-TESM and shRNA technologies, we developed a disease modelling strategy to induce distinct genetic deficiencies in a single hiPSC-derived myogenic progenitor cell line within 1 week. Results As proof of principle, we recapitulated disease-associated pathology of Duchenne muscular dystrophy and limb-girdle muscular dystrophy type 2A caused by loss of function of DMD and CAPN3, respectively. shRNA-mediated knock down of DMD or CAPN3 induced a loss of contractile function, disruption of tissue architecture, and disease-specific proteomes. Pathology in DMD-deficient 3D-TESMs was partially rescued by a candidate gene therapy treatment using micro-dystrophin, with similar efficacy compared to animal models. Conclusions These results show that isogenic shRNA-based humanized 3D-TESM models provide a fast, cheap, and efficient tool to model muscular dystrophies and are useful for the preclinical evaluation of novel therapies.
2024-02-14 | Engineered mischarged transfer RNAs for correcting pathogenic missense mutations.
Missense mutations account for approximately 50% of pathogenic mutations in human genetic diseases, and most lack effective treatments. Gene therapies, gene editing, and RNA therapies, including transfer RNA (tRNA) modalities, are common strategies for genetic disease treatments. However, reported tRNA therapies are for nonsense mutations only. It has not been explored how tRNAs can be engineered to correct missense mutations. Here, we describe missense-correcting tRNAs (mc-tRNAs) as a potential therapeutic for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs charged with one amino acid, but read codons of another in translation. We first developed a series of fluorescent protein-based reporters that indicate the successful correction of missense mutations via restoration of fluorescence. We engineered mc-tRNAs that effectively corrected serine and arginine missense mutations in the reporters and confirmed the amino acid substitution by mass spectrometry and mc-tRNA expression by sequencing. We examined the transcriptome response to mc-tRNA expression and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an mc-tRNA to rescue a pathogenic CAPN3 Arg-to-Gln mutant involved in LGMD2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
Access all drug discovery papers and probability of success in trials forecasts:
Access all drug discovery papers and probability of success in trials forecasts:
Drug Discovery Landscape
2 orphan drug designations for Calpain-3-related limb-girdle muscular dystrophy R1.
2 orphan drug designations for Calpain-3-related limb-girdle muscular dystrophy R1.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
adeno-associated virus serotype 9/rh74 containing the human Capn3 gene and a target sequence of cardiac-specific microRNA | gene therapies | FDA | 2024-01-04 | — | Atamyo Therapeutics |
Adeno associated viral vector serotype 1 containing the human calpain 3 gene | gene therapies | EMA | 2006-04-06 | — | Genethon |
Let's accelerate rare disease drug discovery
Let's accelerate drug discovery
Get access to Explority AI’s forecasts to outperform average preclinical success rates. Whether you’re expanding your R&D pipeline, evaluating a partnership, or simply have a question — we’d love to hear from you.