holoprosencephaly
Pronunciation: hol-oh-pros-en-SEF-ah-lee
Congenital brain malformation where the cerebral hemispheres fail to separate properly during development.
Full Definition
Holoprosencephaly is a complex brain malformation resulting from incomplete separation of the developing forebrain (prosencephalon) into distinct cerebral hemispheres. This condition occurs during early embryonic development and represents a spectrum of severity from alobar (most severe) to semilobar to lobar (mildest) forms. Associated facial abnormalities may include cyclopia, proboscis, cleft lip and palate, and single central incisor. The condition is often associated with chromosomal abnormalities, particularly trisomy 13, and maternal diabetes. In pediatric pathology, gross examination reveals varying degrees of hemispheric fusion, and microscopic findings include architectural disorganization of brain tissue.
Usage
Usage note: Subtypes (alobar, semilobar, lobar) should be specified when known. Often abbreviated as HPE in clinical notes.
In Context
- "Fetal autopsy revealed alobar holoprosencephaly with associated facial dysmorphism." — Perinatal autopsy report
- "MRI findings were consistent with semilobar holoprosencephaly with partial separation of the frontal horns." — Radiology report