Muscle acetylcholinesterase in childhood myopathies

The activities and the molecular forms of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were examined in 28 biopsies of quadriceps femoris muscle from children with a myopathic non-dystrophic disease. These cases were compared with biopsies from 7 children with a neurogenic damage, 14 children with muscular dystrophy and 12 controls. All the biopsies, histochemically stained for AChE, showed no endplates; electron microscopy of muscle fibers from diseased biopsies revealed a diffuse AChE reaction on the fiber surfaces which was not associated with any endplate structure. The AChE activities in NaCl/Triton X-100 extracts from the three groups of patients were all more or less the same, and average levels were similar to those evidenced in controls. The complete disappearance of heavy and medium forms of AChE was noted in 60% of myopathic non-dystrophic patients. We never observed the pattern characteristic to these patients in the biopsies from neurogenic and dystrophic patients or from controls, which displayed a high variability in the profiles of AChE molecular forms.