Generation of a novel Dysferlin microdeletion knock-in mouse model mimicking muscular dystrophy–like pathology

Limb-Girdle Muscular Dystrophy type R2 (LGMD-R2) is caused by mutations in the DYSFERLIN (DYSF) gene, leading to progressive muscle weakness and defective membrane repair. In our previous study, we identified a novel five-nucleotide microdeletion in DYSF (c.3014_3018delACCAG; NM_001130455.2) in Taiwanese LGMD patients, which is predicted to cause a frameshift and premature termination, potentially producing a truncated ~ 108 kDa dysferlin protein. To investigate its pathogenic consequences in vivo, we generated a Dysf microdeletion knock-in mouse model (DysfΔ5/Δ5) to recapitulate the patient-relevant genetic lesion and associated muscular dystrophy–like phenotypes. DysfΔ5/Δ5 mice exhibited undetectable dysferlin expression, impaired rotarod performance, and progressive pathological changes, including increased centrally nucleated fibers, and adipocyte infiltration within skeletal muscle tissues. Immunostaining of muscle tissues revealed disrupted sarcoglycan localization; furthermore, a trend toward macrophage accumulation was observed. Proteomic profiling quantified 2,329 proteins in skeletal muscle from DysfΔ5/Δ5 and wild-type mice, revealing a remodeling proteomic signature in DysfΔ5/Δ5 muscle. Gene Ontology enrichment highlighted lipid catabolic/metabolic processes alongside reduced representation of muscle development, sarcomeric organization, and contractile programs, consistent with dystrophic remodeling and fatty/fibrotic replacement. Together, these results indicate that Dysf Δ5/Δ5 mice exhibit muscular dystrophy–like pathological and functional features consistent with dysferlinopathy, providing a useful platform for mechanistic investigation and preclinical proof-of-concept studies.