Down syndrome

Table of Contents

References & Edit History Quick Facts & Related Topics

Images

Teenager with Down syndrome

karyotype; Down syndrome

For Students

Down syndrome summary

Read Next

People wearing surgical masks (also called face mask or medical masks or safety masks) walk through the city center of Milan, Italy on Feb. 23, 2020. Coronavirus disease COVID-19 pandemic

How Do Face Masks Control the Spread of Disease?

Scanning electron micrograph showing the spiral-shaped bacteria of the genus Leptospira. These organisms cause leptospirosis.

8 Zoonotic Diseases

close up of 3d microscopic blue bacteria

What Was Life Like Before We Knew About Germs?

Hand washing. Healthcare worker washing hands in hospital sink under running water. contagious diseases wash hands, handwashing hygiene, virus, human health

17 Questions About Health and Wellness Answered

Discover

African Americans demonstrating for voting rights in front of the White House as police and others watch, March 12, 1965. One sign reads, "We demand the right to vote everywhere." Voting Rights Act, civil rights.

Timeline of the American Civil Rights Movement

New Zealand. Political/Physical map. Includes locator.

Where Is “Old Zealand”?

Titanic infographic. The 30th anniversary of its discovery is September 1, 2015. SPOTLIGHT VERSION.

Timeline of the Titanic’s Final Hours

Hemp (Cannabis sativa).

9 Mind-Altering Plants

Rural Irish landscape, Sligo, Ireland.

Why Is Ireland Two Countries?

illustration of the walking titanosaurus, Patagotitan mayorum

Titanosaurs: 8 of the World's Biggest Dinosaurs

King Cobra snake in Malaysia. (reptile)

9 of the World’s Deadliest Snakes

Down syndrome: Facts & Related Content

Written and fact-checked by The Information Architects of Encyclopaedia Britannica

News •

First participant with Down syndrome joins Alzheimer's prevention trial • Apr. 12, 2025, 2:47 AM ET (Medical Xpress)

Programme to raise awareness about Down Syndrome held in three metro rail stations • Mar. 30, 2025, 9:53 AM ET (The Hindu)

CMC organises awareness programme to mark world down syndrome • Mar. 25, 2025, 8:51 AM ET (The Hindu)

Jack's Baskets delivers 10,000th basket of support for Down syndrome newborns • Mar. 22, 2025, 5:12 AM ET (CBS)

Facts

Also Known As	trisomy 21 • mongolism • Down’s syndrome

Photos

Teenager with Down syndrome

karyotype; Down syndrome

See All Images →

Topics

trisomy 13 trisomy 18 XYY-trisomy trisomy X

Key People

Gregg L. Semenza

American physician

Quiz

A Yorkshire terrier dressed up as a veterinarian or doctor on a white background. (dogs)

A Visit with the Word Doctor: Medical Vocabulary Quiz

3d illustration human heart. Adult Anatomy Aorta Black Blood Vessel Cardiovascular System Coronary Artery Coronary Sinus Front View Glowing Human Artery Human Heart Human Internal Organ Medical X-ray Myocardium

Medical Terms and Pioneers Quiz

44 Questions from Britannica’s Most Popular Health and Medicine Quizzes