Isolated cerebellar agenesis

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Isolated cerebellar agenesis

ORPHA:1398Morphological anomaly

Also called Near total absence of cerebellum · Subtotal absence of cerebellum

What it is

A rare non-syndromic central nervous system malformation characterized by complete or near-complete absence of the cerebellum with a normal sized posterior fossa, possibly accompanied by hypoplasia of the brainstem. The clinical picture is highly variable, but typically includes ataxia, dysarthria, tremor, dysmetria, dysdiadochokinesia, and oculomotor abnormalities, in addition to impaired mental, motor, and language development and intellectual disability.

Key facts

Age of onset
Childhood
Classified as
Morphological anomaly

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 10008033UMLS C0344488

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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