[Centronuclear myopathy with autosomal dominant inheritance(author's transl)].

For the first time in Germany cases of a "centronuclear myopathy" are described in a 14-year-old boy and his 18-year-old sister. First symptoms in both patients appeared at 4 to 5 years of age with a "sleepy facial expression", clumsy gait and rapid fatigue. Within few years the disease progressed to generalized muscle weakness and atrophy, ptosis, ophthalmoplegia externa and areflexia. Weakness and atrophy were most pronounced in the distal muscles of the lower extremities. Both patients were free of epilepsy and the EEG recordings were normal. Motor and sensory nerve conduction velocities were normal. Repetitive stimulation of nerves revealed a normal transmission from nerve to muscle. Muscle biopsy showed a type I muscle fiber hypotrophy and a type II muscle fibre hypertrophy in addition to a predominance of type I fibres. Both fibre types showed central nuclei, sometimes appearing as chains in longitudinal sections. In most cells with central nuclei there persists a very small pericentral zone free of myofibrils but with increased activity of oxidative enzymes and phosphorylase. 2--3% of muscle fibres in cross sections showed a decreased of absent enzyme activity in the most peripheral fibre zone. Electron microscopy showed evidence of a centrally distinct myofibrillar disintegration. The father of both children had a ptosis at least from the 20th year of age. 5 years later generalized progressive muscle atrophy was recorded. Aged 51 years he died of pneumonia. Though not proved most probably the father suffered from the same disease as the children, pointing to an autosomal dominant inheritance in this family. The disease, according to the literature, seems to be genetically heterogeneous. The clinical picture seems to be independent of the mode of inheritance. Our patients showed a relatively rapid progression of symptoms. Pathogenetically the "centronuclear myopathy" may result from a disturbance of correlated nerve-muscle structures starting during early fetal life.