Dysferlin‐deficient muscular dystrophy features amyloidosis

Abstract

Dysferlin (DYSF) gene mutations cause limb girdle muscular dystrophy type 2B and Miyoshi's myopathy. The consequences of DYSF mutations on protein structure are poorly understood. The gene encoding dysferlin was sequenced in patients with suspected dysferlin-deficient muscular dystrophy. Muscle biopsy specimens were analyzed by histochemistry, immunohistochemistry, and electron microscopy. Antibodies against N-terminal dysferlin-peptides were raised. We found three families with muscular dystrophy caused by homozygous or compound heterozygous DYSF mutations featuring sarcolemmal and interstitial amyloid deposits. These mutations were all located in the N-terminal region of the protein. Dysferlin was a constituent of the amyloid deposits. Limb girdle muscular dystrophy type 2B is the first muscular dystrophy associated with amyloidosis. Molecular treatment strategies will necessarily have to consider the presence of amyloidogenesis.