MedGen

Holoprosencephaly (HPE) is the most commonly occurring congenital structural forebrain anomaly in humans. HPE is associated with mental retardation and craniofacial malformations. Considerable heterogeneity in the genetic causes of HPE has been demonstrated (Ming et al., 2002). For general phenotypic information and a discussion of genetic heterogeneity of holoprosencephaly, see HPE1 (236100). [from OMIM]

An abnormal degree of flatness of the Ala of nose, which can be defined as a reduced nasal elevation index (lateral depth of the nose from the tip of the nose to the insertion of the nasal ala in the cheek x 100 divided by the side-to-side breadth of the nasal alae). [from HPO]