Electron Microscopy of Fibroblasts from Myotonic Muscular Dystrophy Patients

Many genetic diseases can be demonstrated in skin cells cultured in vitro from patients with inborn errors of metabolism. Since myotonic muscular dystrophy (MMD) affects many organs other than muscle, it seems likely that this defect also might be expressed in fibroblasts. Detection of an alteration in cultured skin fibroblasts from patients would provide a valuable tool in the study of the disease as it would present a readily accessible and controllable system for examination. Furthermore, fibroblast expression would allow diagnosis of fetal and presumptomatic cases. An unusual staining pattern of MMD cultured skin fibroblasts as seen by light microscopy, namely, an increase in alcianophilia and metachromasia, has been reported; both these techniques suggest an altered glycosaminoglycan metabolism An altered growth pattern has also been described. One reference on cultured skin fibroblasts from a different dystrophy (Duchenne Muscular Dystrophy) reports increased cytoplasmic inclusions seen by electron microscopy. Also, ultrastructural alterations have been reported in muscle and thalamus biopsies from MMD patients, but no electron microscopical data is available on MMD cultured skin fibroblasts.