Isolated rhombencephalosynapsis

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Isolated rhombencephalosynapsis

ORPHA:59315Malformation syndrome

What it is

A rare cerebellar malformation characterized by congenital complete or partial fusion of the cerebellar hemispheres, dentate nuclei, and middle cerebellar peduncles, and complete or partial absence of the vermis. It may occur as an isolated anomaly or with other malformations of the brain.

Key facts

Prevalence
<1 / 1 000 000
Age of onset
Antenatal, Infancy, Neonatal
Inheritance
Not applicable
Classified as
Malformation syndrome

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

ICD-10 codes

Q04.3filed under a broader ICD-10 category — shared with 75 other rare diseases

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references

MEDDRA 10090354MONDO 0018946UMLS C1866130

Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.

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