Agenesis and dysgenesis of the corpus callosum.

Agenesis and dysgenesis of the corpus callosum is a frequent anomaly that presents with a spectrum of clinical features and exhibits variable findings in neurological studies. Clinical signs and symptoms are the result of cerebral and extracerebral malformations associated with callosal dysgenesis. Callosal agenesis may be an isolated anomaly or may be syndromic as part of more extensive malformations, metabolic and genetic disorders. The advent of modern techniques and equipment for neuroimaging have allowed us to define with more precision the type and severity of the callosal dysgenesis and accompanying other cerebral malformations. Molecular genetic studies allow the recognition and confirmation of new syndromes that until now were incompletely defined. In the context of these new pathologic entities, a new classification is proposed that may prove to be more useful than the traditional single category, "agenesis of the corpus callosum" and can serve as a basis for a later, more detailed, etiologic classification that integrates morphology and molecular genetics.