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Any X-linked syndromic intellectual disability in which the cause of the disease is a mutation in the USP9X gene.
Features include always present findings: Global developmental delay; and common findings: Anal atresia, Hearing loss (hearing impairment), Generalized hypotonia, and Abnormal cortical gyration and others. 57 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 6 | Seizure, Intellectual disability, Global developmental delay |
Arms and legs | 4 | Short foot, Tapered finger, Lower limb asymmetry |
Eyes | 2 | Strabismus, Cataract |
Head and neck | 2 | Cleft palate, Facial asymmetry |
Bones and joints | 2 | Joint hypermobility, Sideways curvature of the spine (scoliosis) |
Lungs and breathing | 2 | Respiratory distress, Recurrent respiratory infections |
Ears | 1 | Hearing loss (hearing impairment) |
Growth and development | 1 | Short stature |
Muscles | 1 | Generalized hypotonia |
Digestive system | 1 | Feeding difficulties |
Kidneys and urinary system | 1 | Renal dysplasia |
Hormones | 1 | Abnormality of thyroid physiology |
Blood and immune system | 1 | Recurrent respiratory infections |
Heart and blood vessels | 1 | Atrial septal defect |
Age of onset: newborn period.
USP9X function has not been fully characterized.
Intellectual disability, X-linked 99, syndromic, female-restricted is associated with mutations in the USP9X gene on chromosome X.
Genetic testing for USP9X is available. Testing is considered confirmatory for diagnosis.
Phenotype severity distribution: 1 always present feature, 15 common features.
No clinical trials have been registered for intellectual disability, X-linked 99, syndromic, female-restricted.
3 publications have been identified in PubMed for intellectual disability, X-linked 99, syndromic, female-restricted. Research spans Case Report / Case Series (67%) and Review / Meta-Analysis (33%).
da Silva Campos TA (2025). [PMID: 40751225](https://pubmed.ncbi.nlm.nih.gov/40751225/). *J Med Case Rep*. [Case Report / Case Series]
Xue S (2025). [PMID: 41240171](https://pubmed.ncbi.nlm.nih.gov/41240171/). *Mol Biol Rep*. [Case Report / Case Series]
Pavlinek A (2024). [PMID: 39092139](https://pubmed.ncbi.nlm.nih.gov/39092139/). *Biol Psychiatry Glob Open Sci*. [Review / Meta-Analysis]
Data assembled from 5 of 12 sources · Last updated Sep 20, 2026, 12:22 PM UTC
Online Mendelian Inheritance in Man