Holoprosencephaly (HPE) is a complex brain malformation resulting from incomplete
cleavage of the prosencephalon, occurring between the 18th and the 28th day of gestation
and affecting both the forebrain and the face. It is estimated to occur in 1/16,000 live births
and 1/250 conceptuses. Three ranges of increasing severity are described: lobar, semi-lobar
and alobar HPE. Another milder subtype of HPE called middle interhemispheric variant
(MIHF) or syntelencephaly is also reported. In most of the cases, facial anomalies are …

Holoprosencephaly is addressed under the following headings: alobar, semilobar, and lobar
holoprosencephaly; arrhinencephaly; agenesis of the corpus callosum; pituitary
abnormalities; hindbrain abnormalities; syntelencephaly; aprosencephaly/atelencephaly;
neural tube defects; facial anomalies; median cleft lip; minor facial anomalies; single
maxillary central incisor; holoprosencephaly‐like phenotype; epidemiology; genetic causes
of holoprosencephaly; teratogenic causes of holoprosencephaly; SHH mutations; ZIC2 …