Title: trisomy 21
Long Title: IUPAC Gold Book - trisomy 21
DOI: 10.1351/goldbook.11325
Status: current

Definition
Presence of an extra chromosome 21.

Notes
1) This produces a characteristic constellation of physical abnormalities with delayed growth and mental development, but is compatible with life into adulthood.
2) The formerly used terms mongoloid and mongolism are now considered offensive.

Related Term
- adulthood: https://goldbook.iupac.org/terms/view/10348

Source
- PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 815 (https://doi.org/10.1515/pac-2015-1202)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/11325/html
- json: https://goldbook.iupac.org/terms/view/11325/json
- xml: https://goldbook.iupac.org/terms/view/11325/xml

Citation: Citation: 'trisomy 21' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.11325
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
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Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-06-13T19:46:13+00:00