Aprosencephaly/atelencephaly spectrum

A group of rare central nervous system malformations characterized by varying degrees of absence or dysplasia of the derivatives of the prosencephalon (i.e. telencephalon and diencephalon), with an intact cranial vault. The spectrum comprises atelencephaly, the less severe form, in which only the telencephalon is affected, and aprosencephaly, where the diencephalon is also involved. The malformations may occur in an isolated form or in association with other anomalies.