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Disease characteristics

Excerpted from the GeneReview: Holoprosencephaly Overview
Holoprosencephaly (HPE) is a structural anomaly of the brain in which there is failed or incomplete separation of the forebrain early in gestation. Classic HPE encompasses a continuum of brain malformations including (in order of decreasing severity): alobar, semilobar, lobar, and middle interhemispheric variant (MIHV) type HPE; a septopreoptic type has also been described. Other CNS abnormalities not specific to HPE may also occur. HPE is accompanied by a spectrum of characteristic craniofacial anomalies in approximately 80% of individuals with HPE. Developmental delay is present in virtually all individuals with the HPE spectrum of CNS anomalies. Seizures and pituitary dysfunction are common. Most affected fetuses do not survive; severely affected children typically do not survive beyond early infancy, while a significant proportion of more mildly affected children survive past 12 months. Mildly manifesting individuals without appreciable brain anomalies on conventional neuroimaging may be described as having “microform” HPE.

Associated genes

Clinical features

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  • Seizure
  • Median cleft lip and palate
  • Micropenis
  • Hypotelorism
  • Adrenal hypoplasia
  • Hypoglycemia
  • Facial cleft
  • Alobar holoprosencephaly
  • Cyclopia
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