FATAL REDUCING BODY MYOPATHY - ULTRASTRUCTURAL AND IMMUNOHISTOCHEMICAL OBSERVATIONS

Two female infants who developed normally during infancy began to have progressive muscle hypotonia and weakness from 2 year 10 months and 2 years 3 months of ages, respectively. Both patients had rapidly progr essive muscle weakness with death from respiratory failure at 4 years 11 months and 3 years 9 months, respectively. In addition to mild infl ammation in their muscle biopsies, the most striking finding was the p resence of numerous reducing bodies (RB) in almost all degenerating fi bers. By electron microscopy, these bodies consisted of fine granular material, usually located around the degenerating nucleus. These bodie s showed no immunohistochemical reaction to antibodies against structu ral, cytoskeletal and membrane proteins and a histone-specific antibod y against nuclei and chromosomes. They were occasionally positively st ained with a ubiquitin antibody. Although the origin of these bodies r emains unknown, they appeared to be related to active myofibrillar deg eneration, probably resulting form primary nuclear degeneration.