X-linked intellectual disability-cerebellar hypoplasia syndrome
Findings
No curated finding names X-linked intellectual disability-cerebellar hypoplasia syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
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.
Definition from the Mondo Disease Ontology (MONDO:0010337), read 2026-09-29. CC BY 4.0.
- Inheritance
- X-linked recessive inheritance
- Onset and course
- Infantile onset
HPO, annotations 2026-09-02
Features
44 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Global developmental delayHPOHP:0001263
- 15 of 15 reported patients
- Very frequent (80% to 99% of cases)
- Intellectual disabilityHPOHP:0001249
- 9 of 9 reported patients
- Very frequent (80% to 99% of cases)
- Cerebellar hypoplasiaHPOHP:0001321
- 1 of 5 reported patients
- Very frequent (80% to 99% of cases)
- Cerebellar vermis hypoplasiaHPOHP:0001320
- 4 of 5 reported patients
- VentriculomegalyHPOHP:0002119
- 4 of 5 reported patients
- Frequent (30% to 79% of cases)
- Abnormal facial shapeHPOHP:0001999
Show the remaining 32
- Generalized myoclonic seizureHPOHP:0002123
- Frequent (30% to 79% of cases)
- HypotoniaHPOHP:0001252
- Frequent (30% to 79% of cases)
- MacrocephalyHPOHP:0000256
- 3 of 5 reported patients
- Moderate intellectual disabilityHPOHP:0002342
- Frequent (30% to 79% of cases)
- Partial absence of cerebellar vermisHPOHP:0002951
- Frequent (30% to 79% of cases)
- Poor speechHPOHP:0002465
- Frequent (30% to 79% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- OPHN1HGNC:8148
- Definitive · ClinGen · X-linked · 2023
- Definitive · G2P · X-linked · 2025
- Strong · Ambry Genetics · X-linked · 2018
- Strong · Labcorp Genetics (formerly Invitae) · X-linked · 2021
- Strong · PanelApp Australia · X-linked · 2025
- Supportive · Orphanet · X-linked · 2021
Where it sits
Other names
3 names
Resolves to: X-linked intellectual disability-cerebellar hypoplasia syndrome
- Also called
- intellectual developmental disorder, X-linked syndromic, Billuart type, X-linked recessiveOligophrenin-1 syndromeOPHN1 syndrome