<unk>  is a type of cephalic disorder. This is a disorder characterized by the failure of the prosencephalon (the forebrain of the embryo) to develop. During normal development the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. (The condition also occurs in other species, as with Cy, the Cyclops kitten.)<unk>  is caused by a failure of the embryo's forebrain to divide to form bilateral cerebral hemispheres (the left and right halves of the brain), causing defects in the development of the face and in brain structure and function.
Holoprosencephaly
Schizencephaly
Hydranencephaly
Lissencephaly
Megalencephaly
Anencephaly
Spina bifida
Deformational plagiocephaly