What is Holoprosencephaly?
Holoprosencephaly (HPE) is a congenital anomaly in which there is incomplete development of the brain. In utero, the developing forebrain (prosencephalon) fails to divide into two separate hemispheres and ventricles. Holoprosencephaly is classified into 4 subtypes: Alobar, Semilobar, Lobar and MIHV.
HPE can range from mild to severe and is classified into four types:
Commonly, parents of children with HPE are given a very dire prognosis and are told that their child has a very small chance of survival. However, the reality is that many children do survive and lead meaningful lives, some of those well into adulthood.
HPE can range from mild to severe and is classified into four types:
- Alobar Holoprosencephaly (severe)--where the brain is not divided and there are severe abnormalities (there is an absence of the interhemispheric fissure, a single primitive ventricle, fused thalami, and absent third ventricle, olfactory bulbs and tracts and optic tracts).
- Semi-Lobar Holoprosencephaly (moderate)--where the brain is partially divided and there are some moderate abnormalities; where there are two hemispheres in the rear but not the front of the brain (there are partially separated cerebral hemispheres and a single ventricular cavity).
- Lobar Holoprosencephaly (mild)--where the brain is divided and there are some mild abnormalities (there is a well developed interhemispheric fissure however there is some fusion of structures).
- Middle Interhemispheric Variant of Holoprosencephaly (MIHV) -- where the middle of the brain (posterior frontal and parietal lobes) are not well separated.
Commonly, parents of children with HPE are given a very dire prognosis and are told that their child has a very small chance of survival. However, the reality is that many children do survive and lead meaningful lives, some of those well into adulthood.