holoprosencephaly

Introduction

genetically & phenotypically variable disorder

Etiology

• results from impaired midline cleavage of the embryonic forebrain resulting in failure to correctly separate into right & left hemispheres

Epidemiology

• the most common structural anomaly of the brain

Pathology

• alobar holoprosencephaly*
  • severest form
  • very small brain with single ventricle, no divisions into hemispheres
  • also associated with cyclopia & proboscis above the single eye, cleft lip/palate, facial cleft
• semilobar holoprosencephaly
• lobar holoprosencephaly

* see also ethmocephaly, cebocephaly

Genetics

• genetically heterogeneous

Clinical manifestations

• associated with several distinct facies & phenotypic variability

More general terms

• dysplasia of cerebral hemispheres
• genetic disease of the central nervous system

More specific terms

• holoprosencephaly type 1 (HPE1)
• holoprosencephaly type 11
• holoprosencephaly type 2 (HPE2)/midline cleft syndrome
• holoprosencephaly type 3 (HPE3)
• holoprosencephaly type 4 (HPE4)
• holoprosencephaly type 5 (HPE5)
• holoprosencephaly type 6 (HPE6)
• holoprosencephaly type 7 (HPE7)
• holoprosencephaly type 9 (pituitary anomalies with holoprosencephaly-like features)

Patient information

holoprosencephaly patient information

Database

• OMIM: https://mirror.omim.org/entry/236100