<unk>  is typically diagnosed during fetal development when there are abnormalities found on fetal brain imaging, however it can also be diagnosed after birth. The Protocol for diagnosis includes neuroimaging (Ultrasound or fetal MRI prior to birth or Ultrasound, MRI or CT post birth), syndrome evaluation, cytogenetics, molecular testing, and genetic counseling. There are four classifications of<unk>  as well as a “microform". These classifications can be distinguished by their anatomical differences. * Alobar<unk>  * Small single forebrain ventricle * No interhemispheric division * Absence of olfactory bulbs and tracts * Absence of corpus callosum * Non separation of deep gray nuclei * Semilobar<unk>  * Rudimentary cerebral lobes * Incomplete interhemispheric division * Absence or hypoplasia of olfactory bulbs and tracts * Absence of corpus callosum * Varying non separation of deep gray nuclei * Lobar<unk>  * Fully-developed cerebral lobes * Distinct interhemispheric division * Midline continuous frontal neocortex * Absent, hypoplasic or normal corpus callosum * Separation of deep gray nuclei * Syntelencephaly, or middle interhemispheric variant of<unk>  (MIHV) * Failure of separation of the posterior frontal and parietal lobes * Callosal genu and splenium normally formed * Absence of corpus callosum * Hypothalamus and lentiform nuclei normally separated * Heterotopic gray matter * Microform * Subtle defects of corpus callosum * Subtle midline brain defects
Holoprosencephaly
Schizencephaly
Hydranencephaly
Hemihydranencephaly
Lissencephaly
Microlissencephaly
Microhydranencephaly
Hemimegalencephaly