Myasthenia gravis is an autosomal recessive disease in which symptoms present in infancy Mother is free of this disease. There is not any fasciculation or areflexia. No antibody bound to acetylcholine receptors is detected. To diagnosis, a typical EMG is necessary. Muscle biopsy is not needed. Treatment with pyridostigmine for a log time, at least in childhood, is needed. This disease, usually, is not progressive.