[Agenesis of the corpus callosum in a man with complete mosaic trisomy 8].

The coexistence in an epileptic patient of a radiologically confirmed agenesis of the corpus callosum and other somatic abnormalities, notably skeletal, prompted us to perform a karyotype which showed an extra chromosome 8. The trisomy 8-callosal agenesis association is not exceptional, but it may easily be missed owing to the absence or scarcity of clinical signs of the cerebral malformation. We would suggest that patients with confirmed agenesis of the corpus callosum should be investigated for trisomy 8 and conversely, that patients with trisomy 8 detected during examination for a characteristic malformative syndrome should be systematically investigated for abnormality of the neocortical commissure.