trisomy 21

Full Definition

Trisomy 21 is a genetic disorder resulting from the presence of a third copy of chromosome 21, causing Down syndrome. This condition leads to intellectual disability, characteristic physical features, and increased risk of certain medical conditions including congenital heart defects and gastrointestinal abnormalities. In pediatric medical writing, trisomy 21 is the preferred medical term over 'Down syndrome' in formal clinical documentation, though both terms may appear in patient education materials.

Usage

Usage note: Preferred over 'Down syndrome' in formal medical documentation; number not hyphenated.

In Context

• "Prenatal screening indicated increased risk for trisomy 21." — Genetic counseling report
• "The infant with trisomy 21 required cardiac evaluation for potential septal defects." — Discharge summary