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intellectual developmental disorder, X-linked, syndromic, Hackmann-Di Donato type - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

intellectual developmental disorder, X-linked, syndromic, Hackmann-Di Donato type

MONDO:0026733

Also known as:intellectual developmental disorder, X-linked, syndromic, Hackman-Di Donato type, X-linked recessiveMRXSHDMental Retardation, X-Linked, With Marfanoid Habitus, 2

Overview

GeneticsX-linked · NKAP (chr X)

OnsetCHILDHOOD

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: Global developmental delay, Low muscle tone (hypotonia), and Disproportionate tall stature; and very common findings: Arachnodactyly, Long face, Joint hypermobility, and Protruding ear. 23 total HPO annotations.

Organ System	Phenotype Count	Example Features
Heart and blood vessels	4	Ventricular septal defect, Aortic root aneurysm, Mitral regurgitation

Genetic Landscape

Assembled from HGNC gene records, ClinGen gene-disease validity evidence, and ClinVar pathogenic variant data. Validity classifications reflect the strength of published evidence linking each gene to this disease.

NKAP encodes NFKB activating protein (415 aa). Acts as a transcriptional repressor. Plays a role as a transcriptional corepressor of the Notch-mediated signaling required for T-cell development. Highest expression in Ovary (9.3 TPM) and Cervix Ectocervix (7.9 TPM).

Intellectual developmental disorder, X-linked, syndromic, Hackmann-Di Donato type is associated with mutations in the NKAP gene on chromosome X.

NKAP is classified as a druggable target (Transcription Factor category) with score 0.0.

Diagnosis

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

Prognosis

Phenotype severity distribution: 3 always present features, 4 very common features, 9 common features.

Data assembled from 4 of 12 sources · Last updated Sep 19, 2026, 5:32 AM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:301039

Questions for Your Care Team

→Should female family members consider carrier screening for NKAP?
→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 developmental disorder, X-linked, syndromic, Hackmann-Di Donato type

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Medical References

External Resources

OMIM

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

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