Normal calpain expression in genetically confirmed limb-girdle muscular dystrophy type 2A.

Abstract

Limb–girdle muscular dystrophy type 2A (LGMD2A) is an autosomal recessive disorder associated with defects in the CAPN3 gene coding for calpain-3, a muscle-specific calcium-activated neutral protease.1 It is characterized by symmetric and selective atrophy and weakness of proximal limb muscles, elevated serum creatine kinase (CK) level, and dystrophic pattern on muscle biopsy.2,3⇓ Clinical differentiation from other LGMD may be difficult, and diagnosis is based mainly on mutation analysis of CAPN3 . Monoclonal antibodies for blots have been developed, but there are not much data regarding the role of protein studies in diagnosis and the correlation between results of protein and genetic studies.4 We report a case of LGMD2A with mutations in the CAPN3 gene but no abnormality in the expression of calpain-3 protein on Western blots. A 43-year-old man had weakness in the proximal arm muscles for 10 years and had recently developed hip weakness. Physical examination revealed scapular winging, wasting of serratus anterior and trapezius muscles, and severe wasting of biceps and brachioradialis muscles with relative hypertrophy of the triceps and forearm muscles. Hamstrings and glutei were also severely affected, …