intellectual disability, X-linked 1
Findings
No curated finding names intellectual disability, X-linked 1 yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
An X-linked dominant condition caused by mutation(s) in the IQSEC2 gene, encoding IQ motif and SEC7 domain-containing protein 2. It is characterized by substantially impaired intellectual functioning and behavioral abnormalities.
Definition from the Mondo Disease Ontology (MONDO:0010656), read 2026-09-29. CC BY 4.0.
- Inheritance
- X-linked dominant inheritance
- Onset and course
- Infantile onset
HPO, annotations 2026-09-02
Features
24 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.
- Atonic seizureHPOHP:0010819
- 1 of 1 reported patient
- Bilateral tonic-clonic seizureHPOHP:0002069
- 1 of 1 reported patient
- Delayed speech and language developmentHPOHP:0000750
- 1 of 1 reported patient
- Developmental regressionHPOHP:0002376
- 1 of 1 reported patient
- Frequent (30% to 79% of cases)
- Intellectual disabilityHPOHP:0001249
- 5 of 6 reported patients · Male
- 4 of 6 reported patients · Female
- 1 of 1 reported patient
- No social interactionHPOHP:0008763
- 1 of 1 reported patient
Show the remaining 12
- Severe intellectual disabilityHPOHP:0010864
- Frequent (30% to 79% of cases)
- Stereotypical hand wringingHPOHP:0012171
- Frequent (30% to 79% of cases)
- Absent speechHPOHP:0001344
- Occasional (5% to 29% of cases)
- Horizontal nystagmusHPOHP:0000666
- Occasional (5% to 29% of cases)
- Hyperkinetic movementsHPOHP:0002487
- Occasional (5% to 29% of cases)
- Inappropriate cryingHPOHP:0030215
- Occasional (5% to 29% 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.
- IQSEC2HGNC:29059
- Definitive · Ambry Genetics · X-linked · 2025
- Definitive · G2P · X-linked · 2015
- Strong · Labcorp Genetics (formerly Invitae) · X-linked · 2023
- Strong · PanelApp Australia · X-linked · 2025
- Supportive · Orphanet · X-linked · 2021
Where it sits
Other names
10 names
Resolves to: intellectual disability, X-linked 1
- Also called
- intellectual developmental disorder, X-linked 1, X-linked dominantIQSEC2-related disorderIQSEC2-related syndromic intellectual disabilitymental retardation, X-linked 1mental retardation, X-linked 18mental retardation, X-linked 78mental retardation, X-linked type 1MRXMRX1MRX78