Limb-girdle muscular dystrophy- type 2C
Limb-girdle muscular dystrophy type 2C: An autosomal recessive form of limb-girdle muscular dystrophy where muscle weakness and atrophy is caused by mutations of the gamma-sarcoglycan gene. The severity of the condition is greatly variable from wheelchair confinement at the age of 9 years to asymptomatic adults. Most tend to live to their third decade. More detailed information about the symptoms, causes, and treatments of Limb-girdle muscular dystrophy type 2C is available below.
Onset is usually in the first or second decade, but it may manifest at a later age with a distal myopathy or elevation of CK levels. Patients have mild-to-moderate proximal weakness with slow-to-moderate progression. Exercise-induced cramps may be present. Calf hypertrophy affects some patients. Adults usually remain ambulant.
Muscular dystrophy is caused by various genetic mechanisms. Duchenne’s and Becker’s muscular dystrophies are X-linked recessive disorders. Both result from defects in the gene coding for the muscle protein dystrophin; the gene has been mapped to the Xp21 locus. The incidence muscular dystrophy is about 1 in 651,450 persons in the United States. Duchenne’s and Becker’s muscular dystrophies affect males almost exclusively. Facioscapulohumeral dystrophy is an autosomal dominant disorder. Limb-girdle dystrophy is usually autosomal recessive. These two types affect both sexes about equally.
Patients may also present with elevated CK levels without weakness but with myalgia and cramps, distal weakness, hypertrophic cardiomyopathy, or rippling-muscle disease. The last condition is mechanical or activity-induced, electrically silent muscle contraction that moves laterally in wavelike fashion across the muscle. Myoedema, or mounding of the muscle after percussion, may be observed. Patients may also have proximal weakness, muscle hypertrophy, or myalgias.