Muscle biopsy from two unrelated patients, a male aged 40 and a female aged 3, with
relatively non-progressive limb weakness since infancy, revealed numerous
subsarcolemmal glassy, hyaline appearing bodies present in 20–30% of the fibres. Type 1
fibre predominance was present, and the hyaline bodies were exclusive to type 1 fibres. The
hyaline bodies were negative with oxidative enzyme and periodic acid-Schiff stains. Electron
microscopy showed the hyaline bodies to contain amorphous granular material of unknown …