T21

Medical abbreviation · Pediatric & Neonatal

T21
Stands forTrisomy 21
CategoriesMedical

T21 stands for Trisomy 21, a pediatric & neonatal abbreviation.

Chromosomal condition caused by an extra copy of chromosome 21, also called Down syndrome, featuring intellectual disability, characteristic facial features and higher rates of heart defects, thyroid disease and leukemia. It is the most common chromosomal condition in live-born babies.

Example: T21 confirmed by karyotype; echocardiogram shows AV canal defect, cardiology follow-up.

Usage notes

John Langdon Down described the syndrome in 1866, and Jérôme Lejeune identified the extra chromosome in 1959. It occurs in roughly 1 in 700 US births, with risk increasing with maternal age. Life expectancy has risen to around 60 years. US style writes "Down syndrome" without a possessive.

More pediatric & neonatal abbreviations

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  • ROP – Retinopathy of prematurity
  • RV – Rotavirus vaccine
  • SBS – Shaken baby syndrome
  • SIDS – Sudden infant death syndrome
  • SUID – Sudden unexpected infant death
  • TcB – Transcutaneous bilirubin
  • TTN – Transient tachypnea of the newborn
  • VAR – Varicella vaccine
  • VFC – Vaccines for Children program
  • VLBW – Very low birth weight
  • WCC – Well-child check

See all 51 pediatric & neonatal abbreviations →

Edited by the AbbreviationList.com team. Spotted an error or a missing meaning? Contact us.

This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.