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intellectual disability, X-linked 99 - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

intellectual disability, X-linked 99

MONDO:0010487

Also known as:USP9X non-syndromic X-linked intellectual disabilityintellectual developmental disorder, X-linked 99, X-linked recessiveintellectual disability, X-linked type 99

Overview

Any non-syndromic X-linked intellectual disability in which the cause of the disease is a mutation in the USP9X gene.

GeneticsX-linked · USP9X (chr X)

OnsetANTENATAL

Clinical Presentation

Built from Human Phenotype Ontology (HPO) phenotype annotations and GeneReviews clinical descriptions. Features represent findings documented across known cases — not an exhaustive list of possible symptoms.

Features include always present findings: Low muscle tone (hypotonia) and Intellectual disability; and common findings: Broad thumb. 17 total HPO annotations.

Organ System	Phenotype Count	Example Features
Brain and nerves	5	Global developmental delay, Aggressive behavior, Autistic behavior

Genetic Landscape

USP9X function has not been fully characterized.

Intellectual disability, X-linked 99 is associated with mutations in the USP9X gene on chromosome X.

Diagnosis

Genetic testing for USP9X is available. Testing is considered confirmatory for diagnosis.

Prognosis

Phenotype severity distribution: 2 always present features, 1 common feature.

Research Landscape

Sourced from ClinicalTrials.gov and PubMed. Publication types are classified using NLM-curated article metadata; research type breakdowns reflect the nature of published work for this disease.

No clinical trials have been registered for intellectual disability, X-linked 99.

16 publications have been identified in PubMed for intellectual disability, X-linked 99. Research spans Case Report / Case Series (31%), Epidemiology / Natural History (31%), and Review / Meta-Analysis (19%).

Research Type	Count	% of Total
Patient case studies	5	31%

Data assembled from 5 of 12 sources · Last updated Sep 19, 2026, 1:09 AM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:300919

GARD

Genetic and Rare Diseases Info Center

GARD:22693

Questions for Your Care Team

→Should female family members consider carrier screening for USP9X?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

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intellectual disability, X-linked 99

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Medical References

External Resources

OMIM

GARD

Questions for Your Care Team

Questions for Your Care Team

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Recent Publications

intellectual disability, X-linked 99

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Medical References

External Resources

OMIM

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

Explore clinical features

Recent Publications