MITOCHONDRIAL DYSFUNCTION WITH MYOCLONUS EPILEPSY AND RAGGED-RED FIBERS POINT MUTATION IN NERVE, MUSCLE, AND ADIPOSE-TISSUE OF A PATIENT WITH MULTIPLE SYMMETRICAL LIPOMATOSIS

We report a 64-year-old man presenting with multiple symmetric lipomat osis (MSL) and mitochondrial encephalomyoneuropathy. The diagnosis of a mitochondrial cytopathy was based on the typical clinical symptoms a nd signs, including chronic progressive external ophthalmoplegia, hear ing impairment, cerebellar ataxia, proximal myopathy, and polyneuropat hy, and on molecular genetic and histological examinations. As a uniqu e finding, the A --> G((8344)), myoclonus epilepsy and ragged-red fibe rs point mutation was found in peripheral nerve, muscle, and adipose t issue. Muscle biopsy revealed multiple ragged-red fibers and other mor phological signs of a mitochondrial myopathy. Sural nerve biopsy demon strated a mixed axonal and demyelinating neuropathy with extensive los s of myelinated fibers and conspicuous onion bulb formations, as well as structural mitochondrial abnormalities on electron microscopy. Thes e findings clearly demonstrate mitochondrial dysfunction in muscle, ad ipose tissue, and for the first time also in nervous tissue of an MSL patient, and strongly support the concept of mitochondrial cytopathy a s one of the possible causes of multiple symmetric lipomatosis. (C) 19 97 John Wiley & Sons, Inc.