Kisho is an information platform, not a medical provider. Nothing on this site constitutes medical advice, diagnosis, or treatment recommendations. All content is aggregated from publicly available sources (including ClinicalTrials.gov, PubMed, FDA.gov, and Orphanet) and is provided for informational purposes only. Clinical trial eligibility, treatment decisions, and any health-related actions should always be discussed with a qualified healthcare professional. Kisho does not endorse any specific therapy, organization, or clinical trial. Terms of use · Privacy policy
Nonspecific X-linked intellectual deficiencies (MRX) belong to the family of sex-linked intellectual deficiencies (XLMR). In contrast to syndromic or specific X-linked intellectual deficiencies (MRXS), which also present with associated physical, neurological and/or psychiatric manifestations, intellectual deficiency is the only symptom of MRX.
No HPO annotations are available for this condition.
Age of onset: infancy, before birth, childhood, adolescence.
At the more severe end of the continuum of RPS6KA3-related intellectual disability (RPS6KA3-ID), clinically described Coffin-Lowry syndrome commonly involves developmental delay, intellectual disability, neurologic manifestations (hypotonia, stimulus-induced drop attacks, spastic paraparesis, and seizures), musculoskeletal manifestations (kyphoscoliosis and pectus deformity), and characteristic craniofacial and hand findings. The milder end of the continuum primarily manifests with neurodevelopmental features and variable but less pronounced multisystem involvement. Some heterozygous females exhibit clinical manifestations that are typically less severe than those seen in males. However, females can have recognizable craniofacial and hand findings that suggest the diagnosis of RPS6KA3-ID. To date, more than 200 individuals have been identified with a pathogenic variant in RPS6KA3. A precise number is not known due to literature reports of individuals who were diagnosed based on clinical features prior to gene identification. The following description of the phenotypic features associated with RPS6KA3-ID is derived from an admixture of reported individuals whose diagnoses were molecularly confirmed as well as reported individuals who were diagnosed based on clinical findings, radiographic findings, and/or family history without molecular confirmation. Affected Males Table 2. RPS6KA3-Related Intellectual Disability: Frequency of Select Features in Males Feature | Frequency1 Development
Developmental delay (typically severe) | +++ (100%) |
|---|---|
Neurologic | Stimulus-induced drop attacks |
Musculoskeletal | Kyphoscoliosis or other spine deformity |
Cardiovascular | Cardiomyopathy |
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
For the purposes of this GeneReview, the terms "male" and "female" are narrowly defined as the individual's biological sex at birth as it determines clinical care .
RPS6KA3-ID should be suspected in a proband with the following suggestive clinical findings, imaging findings, and family history.
Males. All individuals have developmental delay/ intellectual disability, typically delayed development, with speech more severely affected than motor skills, and moderate-to-severe intellectual disability. Other findings in some individuals:
• Neurologic features
Hypotonia
Stimulus-induced drop attacks
Progressive spasticity/paraplegia
Seizures
• Musculoskeletal features
Kyphoscoliosis of childhood onset that is often progressive
Pectus carinatum and/or excavatum
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
Individuals with phenotypic findings suggestive of Coffin-Lowry syndrome (the more severe end of the RPS6KA3-related intellectual disability phenotypic continuum). See .
Table 3.
Disorders of Interest in the Differential Diagnosis of Coffin-Lowry Syndrome
Gene/ Genetic Mechanism | Disorder | MOI | Clinical Characteristics/ Comment
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
Biomarker and diagnostic research for non-syndromic X-linked intellectual disability has been reported in the published literature.
No approved treatments are currently available for non-syndromic X-linked intellectual disability. The disease remains an area of unmet medical need.
No clinical practice guidelines for RPS6KA3-related intellectual disability (RPS6KA3-ID) have been published. Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with RPS6KA3-ID, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended. Table 4. Recommended Evaluations Following Initial Diagnosis in Individuals with RPS6KA3-Related Intellectual Disability
System/Concern | Evaluation | Comment |
|---|---|---|
Development | Developmental assessment | To incl motor, adaptive, cognitive, speech-language eval; Eval for early intervention/ special education Neurobehavioral/ |
Psychiatric | Neuropsychiatric eval | For persons age 12 mos: screening for behavior concerns incl sleep disturbances, ADHD, /or findings suggestive of ASD |
Neurologic | Neurologic eval | To assess for SIDAs, changes in gait or in bowel or bladder function, seizures or movement disorder; Consider EEG if seizures are a concern. |
Musculoskeletal | Orthopedics/ physical medicine rehab/ PT OT eval | To incl assessment of:; Gross motor fine motor skills; Kyphoscoliosis; Pectus deformity; Contractures; Mobility, ADL, need for adaptive devices; Need for PT (to improve gross motor skills) /or OT (to improve fine motor skills) |
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
Care should be taken to avoid specific stimuli that are known to trigger SIDAs in a given individual. Physical activity may be limited due to valvular disease as recommended by a cardiologist.
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
View trials for non-syndromic X-linked intellectual disability
To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 6. Recommended Surveillance for Individuals with RPS6KA3-Related Intellectual Disability
System/Concern | Evaluation | Frequency |
|---|---|---|
Development | Monitor developmental progress educational needs. | At each visit Neurobehavioral/ Psychiatric |
Neurologic | Monitor those w/SIDAs, spasticity, or seizures. | Per treating neurologist Assess for new/worsening signs/symptoms of spinal canal narrowing, incl changes in tone, gait, bowel/bladder habits, expression of pain, focal neurologic changes such as clonus or abnormal tendon reflexes. |
Musculoskeletal | Physical medicine, OT/PT assessment of mobility, self-help skills | At each visit Monitor those w/kyphoscoliosis or pectus deformity for progression. |
Cardiovascular | Monitor those w/cardiomyopathy, valve dysfunction, or other abnormalities. | Per treating cardiologist Assess for new onset of cardiomyopathy. |
Source: GeneReviews — "RPS6KA3-Related Intellectual Disability"
Estimated prevalence: Unknown (Unknown prevalence).
No clinical trials have been registered for non-syndromic X-linked intellectual disability.
15 publications have been identified in PubMed for non-syndromic X-linked intellectual disability. Research spans Basic Science / Preclinical (29%), Review / Meta-Analysis (21%), and Case Report / Case Series (21%).
Research Type | Count | % of Total |
|---|---|---|
Laboratory research | 4 | 29% |
Research summaries | 3 | 21% |
Patient case studies | 3 | 21% |
Other research | 1 | 7% |
Testing and diagnosis research | 1 | 7% |
Clinical study results | 1 | 7% |
Disease patterns and progression | 1 | 7% |
Nunes IS (2026). [PMID: 41087597](https://pubmed.ncbi.nlm.nih.gov/41087597/). *J Hum Genet*. [Case Report / Case Series]
Tkemladze T (2026). [PMID: 41044236](https://pubmed.ncbi.nlm.nih.gov/41044236/). *Eur J Hum Genet*. [Diagnostic / Biomarker]
Liedtke D (2026). [PMID: 41959831](https://pubmed.ncbi.nlm.nih.gov/41959831/). *medRxiv*. [Basic Science / Preclinical]
Xiao H (2025). [PMID: 41094371](https://pubmed.ncbi.nlm.nih.gov/41094371/). *BMC Neurol*. [Review / Meta-Analysis]
Grover A (2025). [PMID: 40057424](https://pubmed.ncbi.nlm.nih.gov/40057424/). *Best Pract Res Clin Endocrinol Metab*. [Review / Meta-Analysis]
Yerlikaya A (2025). [PMID: 41175261](https://pubmed.ncbi.nlm.nih.gov/41175261/). *Mol Biol Rep*. [Review / Meta-Analysis]
Dobrigna M (2025). [PMID: 41223971](https://pubmed.ncbi.nlm.nih.gov/41223971/). *Neurobiol Dis*. [Basic Science / Preclinical]
Aristidou C (2025). [PMID: 41153441](https://pubmed.ncbi.nlm.nih.gov/41153441/). *Genes (Basel)*. [Case Report / Case Series]
Ishiguro K (2025). [PMID: 40483304](https://pubmed.ncbi.nlm.nih.gov/40483304/). *Commun Biol*. [Basic Science / Preclinical]
Gouveia Lopes M (2025). [PMID: 40922895](https://pubmed.ncbi.nlm.nih.gov/40922895/). *Cureus*. [Other]
Data assembled from 4 of 12 sources · Last updated Oct 4, 2026, 12:12 AM UTC
European rare disease database
Genetic and Rare Diseases Info Center
Cardiology eval |
To incl assessment of:; Cardiomyopathy; Valve dysfunction or other abnormalities |
Growth | Measurement of height, weight, head circumference | With attention to pattern of height growth under expectation of stature but normal growth velocity |
Dental | Dental eval | To incl assessment of:; Small or malpositioned teeth; Advanced or delayed eruption of primary teeth; Hypodontia of secondary teeth; Premature tooth loss |
Hearing | Audiologic eval | Assess for sensorineural hearing loss. |
Eyes | Ophthalmologic eval | To assess for vision, abnormal ocular movement, best corrected visual acuity, refractive errors, strabismus, blepharitis, more complex findings (e.g., cataract, retinal pigment atrophy, optic atrophy) that may require referral for subspecialty care /or low vision services |
Respiratory | Sleep medicine eval | To assess for obstructive sleep apnea; Refer to pulmonologist to evaluate for restrictive lung disease if severe kyphoscoliosis or concerning respiratory symptoms are present. |
Genetic counseling | By genetics professionals1 | To inform affected persons their families re nature, MOI, implications of RPS6KA3-ID to facilitate medical personal decision making Family support resources |
Treatment of Manifestations in Individuals with RPS6KA3-Related Intellectual Disability Manifestation/Concern | Treatment | Considerations/Other Developmental delay/ Intellectual disability/ Neurobehavioral/ |
psychiatric issues | See | Risperidone may be of benefit to persons who display destructive or self-injurious behavior . |
Paraplegia | Orthopedics/ physical medicine rehab/ PT OT incl stretching to help avoid contractures falls | Consider n... |