LGMDs represent a heterogeneous group of inherited disorders primarily affecting the pelvic and shoulder girdle muscles, leading to muscle weakness and wasting. These conditions exhibit dystrophic muscle histology, characterized by:
- Ongoing degeneration of muscle fibers
- Increased variability in fiber size
- Replacement of muscle tissue by fat and connective tissue.
Clinical Spectrum
The clinical presentation of LGMDs varies widely:
- Severe forms: Early onset in the first decade, rapid progression, and a phenotype resembling Duchenne Muscular Dystrophy (DMD).
- Milder forms: Later onset, slower progression, and reduced severity.
Common Features
- Predominantly proximal muscle weakness.
- Sparing of facial, extraocular, and distal limb muscles.
- Significant variability in progression even within specific genetic subtypes.