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partial duplication of the long arm of chromosome X - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

partial duplication of the long arm of chromosome X

MONDO:0017010

Also known as:partial duplication of chromosome Xqpartial duplication of the long arm of chromosome type Xpartial trisomy of chromosome Xq

Overview

Chromosome Xq duplication is a chromosome abnormality that affects many different parts of the body. People with this condition have an extra copy of the genetic material located on the long arm (q) of the X chromosome in each cell. The severity of the condition and the associated signs and symptoms vary based on the size and location of theduplication;the genes involved; and the sex of the affected person. In general, males are typically more severely affected than females and often experience intellectual disability, developmental delay, short stature, abnormalities of the reproductive organs, anddistinctive craniofacial features. Many females with this duplication do not have any symptoms or are only affected with short stature; however, some may be just as severely affected as males with the condition. Most cases are inherited in an X-linked manner, often from a mother with no signs or symptoms of the condition. Treatment is based on the signs and symptoms present in each person.

OnsetCONGENITAL, CHILDHOOD

ResearchLimited published research (4 articles)

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.

No HPO annotations are available for this condition.

Age of onset: at birth, childhood.

GeneReviews

Clinical Guidance

MECP2 duplication syndrome is an X-linked disorder, mainly affecting males. The core phenotype includes developmental delay / intellectual disability, infantile hypotonia, speech and motor delay, recurrent infections, seizures, and gastrointestinal dysfunction. Additional, less frequent clinical features have been described. More than 300 affected males have been reported to date and the clinical findings are consistent in all reports [, , , , , , , , , , , , , , , , ]. Table 2. Select Features of MECP2 Duplication Syndrome

Diagnosis

Drawn from GeneReviews diagnostic guidelines, newborn screening panel status (RUSP), and ClinGen gene-disease validity classifications. Reflects current clinical evidence and consensus where available.

GeneReviews

Diagnostic Criteria

Suggestive Findings

MECP2 duplication syndrome should be considered in males with the following clinical findings:

Severe-to-profound intellectual disability with limited or absent speech
Early-onset hypotonia with very slow motor development
Progressive spasticity predominantly of the lower limbs

Treatment

Compiled from FDA-approved drug records, orphan drug designations, and FDA Adverse Event Reporting System (FAERS) safety data. GeneReviews management guidance is included where available.

No approved treatments are currently available for partial duplication of the long arm of chromosome X. The disease remains an area of unmet medical need.

GeneReviews

Management Guidelines

Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with MECP2 duplication syndrome, the evaluations summarized (if not performed as part of the evaluation that led to diagnosis) are recommended. Table 3. Recommended Evaluations Following Initial Diagnosis in Individuals with MECP2 Duplication Syndrome

Prognosis

Based on GeneReviews surveillance recommendations, HPO phenotype frequency and severity annotations, and published prevalence estimates from Orphanet and OMIM.

GeneReviews

Surveillance Guidelines

Table 5.

Recommended Surveillance for Individuals with MECP2 Duplication Syndrome

System/Concern | Evaluation | Frequency

Feeding

| • Measurement of growth parameters

Eval of nutritional status safety of oral intake

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 partial duplication of the long arm of chromosome X.

4 publications have been identified in PubMed for partial duplication of the long arm of chromosome X. Research spans Case Report / Case Series (50%), Diagnostic / Biomarker (25%), and Basic Science / Preclinical (25%).

Recent Publications

Ghatanatti J (2025). [PMID: 39944420](https://pubmed.ncbi.nlm.nih.gov/39944420/). *Cureus*. [Case Report / Case Series]
Hartanto AI (2025). [PMID: 40787125](https://pubmed.ncbi.nlm.nih.gov/40787125/). *Int Med Case Rep J*. [Case Report / Case Series]
Guo C (2024). [PMID: 39707235](https://pubmed.ncbi.nlm.nih.gov/39707235/). *BMC Pregnancy Childbirth*. [Diagnostic / Biomarker]
Pehlivan D (2024). [PMID: 39696717](https://pubmed.ncbi.nlm.nih.gov/39696717/). *Genome Med*. [Basic Science / Preclinical]

Data assembled from 4 of 12 sources · Last updated Sep 20, 2026, 4:39 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

Orphanet

European rare disease database

Orphanet:263783

GARD

Genetic and Rare Diseases Info Center

GARD:5369

Questions for Your Care Team

→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

← Back to All Diseases

Feature	% of MALES w/Feature	Comment
Intellectual disability	100%	Most males have moderate-to-severe intellectual disability.
Infantile hypotonia	95%	—
Feeding issues	60%	—
Constipation	61%	—
Walk independently or w/support	55%	—
Spasticity	65%	Can be an underestimation given that this feature is age related
Seizures	~50%	—
Recurrent infections	75%	Most often affecting the respiratory tract
Nonspecific anomalies on brain imaging	69%	Feeding/gastrointestinal manifestations. During the first weeks of life, feeding difficulties resulting from hypotonia may become evident in affected males.

System/Concern	Evaluation	Comment
Feeding	Gastroenterology/ nutrition/ feeding team eval	To incl eval of aspiration risk nutritional status; Consider eval for gastric tube placement in those w/dysphagia /or aspiration risk.
Development	Developmental assessment	To incl motor, adaptive, cognitive, speech/language eval; Eval for early intervention/ special education
Musculoskeletal	Orthopedics/ physical medicine rehab/ PT OT eval	To include assessment of:; Gross motor fine motor skills; Contractures, spasticity; Mobility, activities of daily living, need for adaptive devices; Need for PT (to improve gross motor skills) /or OT (to improve fine motor skills)
Neurologic	Neurologic eval	Consider EEG if seizures are a concern.
Immunologic	Clinical assessment for history risk of recurrent infections	Psychiatric/
Behavioral	Neuropsychiatric eval	For persons age 12 mos: screening for behavior concerns incl ADHD, anxiety, /or traits suggestive of ASD Genetic
counseling	By genetics professionals1	To inform affected persons families re nature, MOI, implications of MECP2 duplication syndrome to facilitate medical personal decision making Family support resources
Treatment of Manifestations in Individuals with MECP2 Duplication Syndrome Manifestation/Concern	Treatment	Considerations/Other Poor weight gain / Failure to thrive
Bowel dysfunction	Monitor for constipation.	Stool softeners, prokinetics, osmotic agents, or laxatives as needed Developmental delay /
Intellectual disability	See .	—
Spasticity	Orthopedics/ physical medicine rehab/ PT OT incl stretching to help avoid contractures falls	Consider need for positioning mobility devices, disability parking placard.; PT w/attention to stretching exercises can help maintain joint range of motion prevent secondary contractures, thus prolonging ability to walk.
Epilepsy	Standardized treatment w/ASMs by experienced neurologist	Many ASMs may be effective; none has been demonstrated effective specifically for this disorder.; Seizure treatment may require multidrug therapy.; Education of parents/caregivers1 Recurrent infections

Kisho

partial duplication of the long arm of chromosome X

Overview

Clinical Presentation

Clinical Guidance

Diagnosis

Diagnostic Criteria

Suggestive Findings

Treatment

Management Guidelines

Prognosis

Surveillance Guidelines

Feeding

Research Landscape

Recent Publications

Medical References

External Resources

Orphanet

GARD

Questions for Your Care Team

Questions for Your Care Team

Differential Diagnosis

Therapies Under Investigation

Clinical Trials

Gastrointestinal

Development

Musculoskeletal

Neurologic

Immunologic

Behavioral

Other

partial duplication of the long arm of chromosome X

Overview

Clinical Presentation

Clinical Guidance

Diagnosis

Diagnostic Criteria

Suggestive Findings

Treatment

Management Guidelines

Prognosis

Surveillance Guidelines

Feeding

Research Landscape

Recent Publications

Medical References

External Resources

Orphanet

GARD

Subtypes

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

Differential Diagnosis

Therapies Under Investigation

Clinical Trials

Gastrointestinal

Development

Musculoskeletal

Neurologic

Immunologic

Behavioral

Other