Septopreoptic holoprosencephaly (HPE) is a very rare subtype of lobar HPE characterized by midline fusion limited to the septal and/or preoptic regions of the telencephalon without a significant frontal neocortical fusion. The disease is Experimental Factor Ontology id EFO_0700068 (septopreoptic holoprosencephaly). Also known as: Septopreoptic HPE.