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tetrasomy 21 - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

tetrasomy 21

MONDO:0019864

Also known as:Isochromosome 21tetrasomy type 21

Overview

Tetrasomy 21 is an extremely rare autosomal anomaly resulting from the presence of 4 copies of chromosome 21, characterized by features of trisomy 21 including developmental delay/intellectual disability, muscular hypotonia, short neck with redundant skin, brachycephaly, microcephaly, flat face, epicanthus, upslanted palpebral fissures, small ears, protruding tongue, single transverse palmar crease, brachydactyly, hypoplastic iliac wings, together with additional features such as prematurity, intrauterine growth retardation, high and broad forehead, hypertelorism. Haematological malignancies are also associated and may occur earlier than in trisomy 21.

ResearchLimited published research (4 articles)

Prognosis

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).

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 tetrasomy 21.

4 publications have been identified in PubMed for tetrasomy 21. Research spans Case Report / Case Series (50%), Basic Science / Preclinical (25%), and Epidemiology / Natural History (25%).

Recent Publications

Liu RY (2026). [PMID: 41730779](https://pubmed.ncbi.nlm.nih.gov/41730779/). *American journal of medical genetics. Part A*. [Epidemiology / Natural History]
Munakata M (2026). [PMID: 40769884](https://pubmed.ncbi.nlm.nih.gov/40769884/). *Fukushima journal of medical science*. [Case Report / Case Series]
Trivedi P (2025). [PMID: 41452352](https://pubmed.ncbi.nlm.nih.gov/41452352/). *Journal of the Association of Genetic Technologists*. [Case Report / Case Series]
Simpson APA (2025). [PMID: 39851542](https://pubmed.ncbi.nlm.nih.gov/39851542/). *Cells*. [Basic Science / Preclinical]

Data assembled from 3 of 12 sources · Last updated Sep 18, 2026, 1:44 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

Orphanet

European rare disease database

Orphanet:96055

GARD

Genetic and Rare Diseases Info Center

GARD:12480

Questions for Your Care Team

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tetrasomy 21

Overview

Prognosis

Research Landscape

Recent Publications

Medical References

External Resources

Orphanet

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team