Table 1

Anatomic classification of HPE -Different levels of severity [1] [6]

ALOBAR (complete)
Small single forebrain ventricle
No interhemispheric division
Absence of olfactory bulbs and tracts
Absence of corpus callosum
Non separation of deep gray nuclei

SEMI-LOBAR
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
Fully-developed cerebral lobes
Distinct interhemispheric division
Midline continuous frontal neocortex
Absent, hypoplasic or normal corpus callosum
Separation of deep gray nuclei

MIHF
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

Dubourg et al. Orphanet Journal of Rare Diseases 2007 2:8   doi:10.1186/1750-1172-2-8