Giant Neuronal Mitochondria in an Infant With Microcephaly and Seizure Disorder

THE application of electron microscopic techniques to the investigation of various neurological diseases has yielded significant contributions for understanding several classical diseases.1,2Furthermore, altered submicroscopic structures such as abnormal synapses and mitochondria were reported as the sole significant abnormality and presumably causal in some disorders. Gonatas and co-workers3,4found abnormal, enlarged presynaptic terminals in the cerebral cortex of two patients who had mental retardation and seizure disorders. Luft and co-workers5demonstrated morphologically abnormal mitochondria in the skeletal muscle of a patient who had a hypermetabolic state of unknown etiology and they found a three to fourfold increase in total mitochondrial protein together with an increased cytochrome activity per unit of mitochondrial protein. Their conclusion was that this was a primary hypermetabolic state, caused by an abnormal quality and type of mitochondria. Following the report of Luft and co-workers, several further cases of myopathy with abnormal mitochondria