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Start free with EleplanX-linked intellectual disability-cerebellar hypoplasia syndrome
ORPHA:137831Disease
Also called OPHN1 syndrome · Oligophrenin-1 syndrome
What it is
X-linked intellectual deficit-cerebellar hypoplasia, also known as OPHN1 syndrome, is a rare syndromic form of cerebellar dysgenesis characterized by moderate to severe intellectual deficit and cerebellar abnormalities.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Infancy, Neonatal
- Inheritance
- X-linked dominant
- Classified as
- Disease
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
Common30–79%
18- Abnormal facial shape
- Abnormality of speech or vocalization
- Ataxia
- Autistic behavior
- Deeply set eye
- Focal impaired awareness seizure
- Generalized hypotonia
- Generalized myoclonic seizure
- Hypotonia
- Intellectual disability, moderate
- Intellectual disability, severe
- Partial absence of cerebellar vermis
- Poor speech
- Reduced eye contact
- Reduced social responsiveness
- Strabismus
- Tall chin
- Ventriculomegaly
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.
Gene
ICD-10 codes
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
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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