Summary
Limb girdle muscular dystrophy (LGMD) constitutes a group of genetically determined, progressive muscle weakness disorders, in which the pelvic or shoulder girdle musculature is predominantly or primarily involved. The prevalence of autosomal recessive and sporadic LGMD cases has been estimated to 1/200,000. The age at onset is extremely variable. The majority probably presents between the ages of 8-15, though a range from 2 to 40 years has been reported. Different subtypes of LGMD can now be distinguished by means of protein- and genetic analysis. Several detailed reports of the phenotype of LGMD2A confirmed its relatively uniform clinical presentation as a predominantly symmetric atrophic muscular dystrophy, with relatively rare muscle hypertrophy. Achilles tendon contractures may be an early sign, and contractures elsewhere may also be prominent. Pelvic girdle involvement is present and symptomatic from the onset. Scapular winging is usually present from the onset. The rate of deterioration varies between families, intrafamilial variation is not very obvious. The disease has a much lesser severity than Duchenne muscular dystrophy, and can be very mild. Respiratory, but not cardiac complications have been described. Confinement to a wheelchair occurs at the earliest 11-18 years after the onset of symptoms. Serum creatine kinase (CK) activity is often more than 20 times elevated. LGMD2A is transmitted as an autosomal recessive form. Among theses cases, 33% are caused by mutation in the gene encoding the proteolytic enzyme calpain-3 (CAPN3) that is located on chromosome 15q15. No specific treatment is known and many patients receive physical therapy to prevent worsening of contractures.
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Last update: October 2004
