Middle interhemispheric variant (MIH) of holoprosencephaly (HPE) or syntelencephaly is a rare variant of HPE characterized by abnormal midline union of the posterior frontal and parietal lobes with variable fusion of thalami. The disease is Experimental Factor Ontology entry EFO_0700113 (midline interhemispheric variant of holoprosencephaly). Also known as: MIH, MIH type HPE, MIHF, MIHV, Syntelencephaly, middle interhemispheric fusion variant, middle interhemispheric variant of holoprosencephaly.