Among 314 patients with classic myasthenia gravis (MG; 254200), Oh and Kuruoglu (1992) found 12 (3.8%) who presented with chronic limb-girdle myasthenia. None of the 12 patients had oculobulbar involvement, which had initially excluded the diagnosis of myasthenia ... Among 314 patients with classic myasthenia gravis (MG; 254200), Oh and Kuruoglu (1992) found 12 (3.8%) who presented with chronic limb-girdle myasthenia. None of the 12 patients had oculobulbar involvement, which had initially excluded the diagnosis of myasthenia gravis. Disease onset occurred between the ages of 28 and 69 years and was characterized by lower proximal muscle weakness, usually followed by upper proximal muscle weakness. All patients showed a decremental response to repetitive nerve stimulation, and all patients had normal serum creatine kinase. Three patients had thymic hyperplasia, 1 patient had systemic lupus erythematosus (SLE; 152700), and 1 patient had hyperthyroidism. Five patients had anti-AChR autoantibodies. All patients improved somewhat with acetycholinesterase inhibitors, and in 8 patients, a form of immunotherapy was needed in addition to improve clinical symptoms. Oh and Kuruoglu (1992) noted that all of their patients had adult onset and that none of them had a family history, thus distinguishing the disorder from familial limb-girdle myasthenia (254300). Azulay et al. (1994) reported 2 unrelated patients with autoimmune limb-girdle myasthenia characterized by adult onset (41 and 62 years, respectively) of proximal muscle weakness and variable atrophy. Both patients had difficulty in walking, climbing stairs, and raising themselves from a sitting position. Electrophysiologic studies showed a decremental motor response to repetitive stimulation. Both patients had AChR autoantibodies and 1 patient responded well to immunotherapy. One patient developed ophthalmoplegia late in the disease. Rodolico et al. (2002) reported 4 patients with autoimmune limb-girdle myasthenia. Age at onset of proximal muscle weakness and wasting ranged from 14 to 42 years. Three patients had thymoma and 1 patient had Hashimoto thyroiditis (140300). EMG showed low muscle unit potentials and decremental response on repetitive nerve stimulation. Treatment with AChE inhibitors was ineffective, but all responded to additional immunotherapy. One of the 4 patients had AChR autoantibodies. Muscle biopsy showed type 2 fiber atrophy in 2 patients and myopathic changes in 2 patients. Rodolico et al. (2002) also reported 5 additional patients with familial limb-girdle myasthenia.