FAMILIAL DESMINOPATHY - MYOPATHY WITH ACCUMULATION OF DESMIN-TYPE INTERMEDIATE FILAMENTS

Two siblings developed cardiomyopathy several years before slowly prog ressive muscle weakness. Skeletal muscle biopsy specimens showed subsa rcolemmal crescents of dark eosinophilic material in both type I and t ype II fibres. Immunohistochemically the subsarcolemmal material stain ed positively for die intermediate filament protein desmin and for the heat shock protein ubiquitin but for no other cytoskeletal proteins. Ultrastructurally the subsarcolemmal deposits consisted of aggregates of granular and filamentous material arising from Z-bands. Follow up m uscle biopsies six years later showed an increased number of the muscl e fibres that contained subsarcolemmal aggregates that stained positiv ely for desmin and ubiquitin. These clinical and pathological features characterise a rare familial myopathy associated with an unusual dist ribution of desmin intermediate filament proteins in skeletal and prob ably also cardiac muscle.