Myonuclear calcium in carriers of Duchenne muscular dystrophy. An X-ray microanalysis study

Electron-microscopic X-ray microanalysis (EMMA) was used to study calcium and phosphorus concentrations in the muscle fibre nuclei of 3 genetically definite, 5 probable and 2 possible carriers of Duchenne muscular dystrophy. All cases showed elevated mean calcium:phosphorus ratios compared with 4 female controls and, with the exception of one possible carrier, all showed elevated calcium concentrations. A significantly greater variation of values was also found for both parameters. Analyses were made of nuclei from fibres showing no morphological abnormalities and the results suggest elevation of myonuclear calcium may be an early defect in dystrophic muscle.