HOLOPROSENCEPHALY / CYCLOPIA

Cyclopia (alobar holoprosencephaly) (OMIM% 236100) is a rare and lethal complex human malformation resulting from incomplete cleavage of prosencephalon into right and left hemispheres occurring between the 18th and the 28th day of gestation.
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There are three levels of alobar holoprosencephaly (cyclopia being the most severe form), with a single brain ventricle and no interhemispheric fissure; semilobar holoprosencephaly with a partial separation; and lobar holoprosencephaly, where the right and left ventricles are separated, but with some continuity across the frontal cortex.