Orphanet: Midline interhemispheric variant of holoprosencephaly

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Midline interhemispheric variant of holoprosencephaly

Disease definition

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:93926

Classification level: Subtype of disorder

Synonym(s):
- MIH
- MIH type HPE
- MIHF
- MIHV
- Middle interhemispheric fusion variant
- Middle interhemispheric variant of holoprosencephaly
- Syntelencephaly
Prevalence: Unknown
Inheritance: Multigenic/multifactorial or Not applicable
Age of onset: Infancy, Neonatal
ICD-10: Q04.2
ICD-11: LA05.2
OMIM: 157170 609637 610829
UMLS: -
MeSH: -
GARD: -
MedDRA: -

Summary

Epidemiology

About 2% to 15% of HPE patients have MIH type.

Clinical description

Patients have rather mild dysmorphic facial features such as ocular hypotelorism, flat or narrow nasal bridge or a relatively normal facial appearance.

Etiology

MIH has mainly been reported in patients with ZIC2 (13q32) mutations.

Prognosis

Prognosis is better than in classical forms of HPE.

Expert reviewer(s): Dr Sandra MERCIER - Pr Sylvie ODENT - Last update: October 2011

A summary on this disease is available in Español (2011) Français (2011) Italiano (2011) Nederlands (2011) Português (2011) Deutsch (2011) Polski (2011, pdf)

Detailed information

Disease review articles

Clinical genetics review
English (2020) - GeneReviews

Genetic Testing

Guidance for genetic testing
English (2010) - Eur J Hum Genet

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FSMR

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