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Key Features of Limb-Girdle Muscular Dystrophy (LGMD)
Definition:
Limb-girdle muscular dystrophy (LGMD) is a group of inherited genetic disorders characterized by progressive muscle weakness and wasting primarily affecting the muscles surrounding the shoulders and hips (limb-girdle).
Classification:
LGMD is classified into several subtypes based on the affected gene and pattern of muscle involvement. Common subtypes include:
LGMD1: Mutations in the sarcoglycan gene complex
LGMD2: Mutations in the dysferlin gene
LGMD3: Mutations in the calpain-3 gene
LGMD4: Mutations in the FKRP gene
Symptoms:
Muscle weakness: Primarily affects the muscles proximal to the limbs, such as the shoulders, hips, thighs, and upper arms.
Muscle wasting: Loss of muscle bulk and strength.
Difficulty walking: Progressive weakness can lead to Gower's sign (using arms to push off the floor to stand up) and frequent falls.
Difficulty lifting objects: Proximal weakness hinders movements such as raising arms or lifting objects.
Scoliosis: Weakness of the trunk muscles can cause a curvature of the spine.
Respiratory problems: Weakness of respiratory muscles can lead to fatigue and shortness of breath.
Diagnosis:
Medical history and physical examination: Evaluation of symptoms and muscle function.
Genetic testing: Identifies mutations in the genes responsible for LGMD.
Muscle biopsy: Analysis of muscle tissue under a microscope to assess muscle damage and inflammation.
Treatment:
There is currently no cure for LGMD.
Treatment focuses on managing symptoms and improving quality of life.
Physical therapy and exercise: To strengthen muscles and improve mobility.
Assistive devices: Such as wheelchairs, braces, and orthoses.
Medications: To manage pain, inflammation, and respiratory issues.
Additional Features:
Age of onset: Varies depending on the subtype, but typically occurs during childhood or adolescence.
Progression: Gradual and variable, with some subtypes progressing more rapidly than others.
Inheritance: Most LGMD subtypes are inherited in an autosomal dominant or autosomal recessive manner.
Lifespan: Life expectancy is generally not significantly affected in mild cases, but it can be reduced in severe cases.
References:
Muscular Dystrophy Association. (n.d.). Limb-Girdle Muscular Dystrophy. https://www.mda.org/disease/limb-girdle-muscular-dystrophy
National Institute of Neurological Disorders and Stroke. (2020, September 16). Limb-Girdle Muscular Dystrophy. https://www.ninds.nih.gov/Disorders/All-Disorders/Limb-Girdle-Muscular-Dystrophy-Information-Page
Emery, A. E. H. (2002). Limb-girdle muscular dystrophy. Lancet, 359(9307), 687-695.
Bonnemann, C. G. (2011). Limb-girdle muscular dystrophies: Genetics, molecular pathophysiology, and emerging therapeutic approaches. Current Opinion in Neurology, 24(5), 467-474.
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