To assess whether these mitochondrial abnormalities observed in human desminopathy muscle are also present in our R349P desmin knock-in mice, corresponding electron microscopy analyses of aged heterozygous R349P desmin knock-in mice were performed, occasionally revealing abnormal fibers with remnants of degenerating myofibrils that were interspaced with an accumulation of enlarged mitochondria (Fig. 3b, middle panels). The gene discussed is DES; the disease is Desminopathy.