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Midline interhemispheric variant of holoprosencephaly
Midline interhemispheric variant of holoprosencephaly (MIH) or syntelencephaly is a form of holoprosencephaly (HPE; see this term) characterized by non-separation of the posterior frontal and parietal lobes, normally-formed callosal genu and splenium, absence of the callosal body, normally-separated hypothalamus and lentiform nucleus, and frequent heterotopic gray matter.
ORPHA:93926Classification level: Subtype of disorder
- MIH type HPE
- Middle interhemispheric fusion variant
- Middle interhemispheric variant of holoprosencephaly
- Prevalence: 1-9 / 100 000
- Inheritance: Multigenic/multifactorial or Not applicable
- Age of onset: Infancy, Neonatal
- ICD-10: Q04.2
- OMIM: 157170 609637 610829
- UMLS: -
- MeSH: -
- GARD: -
- MedDRA: -
About 2% to 15% of HPE patients have MIH type.
Patients have rather mild dysmorphic facial features such as ocular hypotelorism, flat or narrow nasal bridge or a relatively normal facial appearance.
MIH has mainly been reported in patients with ZIC2 (13q32) mutations.
Prognosis is better than in classical forms of HPE.