A defect of development of the brain characterized by absence of the telencephalon (embryonic structure from which the mature cerebrum develops).
Comment:
Atelencephaly can be differentiated from anencephaly by the presence of a skull and an intact scalp. Aprosencephaly is characterized by absence of the telencephalon and diencephalon (embryonic structure from which the thalamus develops). Atelencephaly is generally fatal.