About Down Syndrome
Down syndrome is the most common chromosomal condition and a natural part of human diversity. It occurs when a person has a full or partial extra copy of chromosome 21, which contributes to each individual’s unique physical and cognitive characteristics.
There are three types of Down syndrome:
- Trisomy 21 – The most common type (about 95% of cases), where every cell contains three copies of chromosome 21.
- Translocation Down syndrome – About 4% of cases. Part or all of an extra chromosome 21 attaches to another chromosome and can sometimes be inherited.
- Mosaic Down syndrome – About 1% of cases. Some cells have the extra chromosome 21, while others have the usual two, creating a mosaic pattern in the body.
Down syndrome occurs across all races, ethnicities, and socioeconomic levels, affecting both males and females equally. Most babies with Down syndrome are born to mothers under 35, reflecting higher birth rates in this age group. Every person with Down syndrome is unique. Common traits may include low muscle tone, smaller stature, upward slant to the eyes, and a single deep crease across the palm. Intellectual abilities typically range from mild to moderate, but this does not limit their talents, skills, or contributions. With supportive care and inclusion, people with Down syndrome attend school, work, make choices about their lives, form meaningful relationships, and contribute fully to their communities.
Facts About Down Syndrome
- Most common chromosomal condition in the U.S.
- Birth prevalence: About 1 in every 640–700 babies in the U.S., roughly 5,700–6,000 babies each year (CDC)
- Population: Over 400,000 people in the U.S. live with Down syndrome (NDSS)
- Occurs across all races, ethnicities, and socioeconomic levels
- Maternal age: Most babies are born to mothers under 35 (CDC)
- Health and medical care: With access to regular medical care, individuals benefit from treatments for heart health, vision, hearing, thyroid function, and overall wellness (CDC)
- Life expectancy: Many individuals now live into their 50s, 60s, and beyond (NIH)
- Community participation: People with Down syndrome attend school, work, form relationships, participate in their communities, and lead fulfilling lives
➡️ Download our one-page Fact Sheet
Language Guidelines
Using respectful, person-centered language promotes dignity, inclusion, and understanding:
- People-first language: Always refer to individuals as people first. Say “a child with Down syndrome” instead of “a Down syndrome child.” Avoid terms like “Down’s child” or “He has Down’s.”
- Condition, not disease: Down syndrome is a condition or syndrome, not a disease.
- Positive phrasing: People have Down syndrome; they do not “suffer from” it.
- Down vs. Down’s: Use Down syndrome (without an apostrophe), per AP Stylebook.
- Intellectual disability: Use “intellectual disability” or “cognitive disability” instead of outdated terms like “mental retardation.”
- Avoid derogatory terms: Never use the “r-word.” It is hurtful and implies that individuals with disabilities are not capable or competent.
