Down syndrome (or Trisomy 21) is a condition in which a person has an extra chromosome.
Around 1 in every 800 babies will be born with Down syndrome. Down syndrome occurs naturally – there is no known cause.
Most people have 23 pairs of chromosomes – 46 in total. People with Down syndrome have an extra chromosome added onto the 21st pair – 47 in total.
Chromosomes act like an instruction manual that defines how our bodies look and how they work.
People who have Down syndrome usually have an intellectual disability. This is different in each person. Some health conditions are more common in people with Down syndrome.
The best people to answer many questions about Down syndrome are people with Down syndrome, so over to them…
All about Chromosomes…
“Chromosomes R Us” is a short film explaining how Down syndrome (or Trisomy 21) occurs.
This film was made by actors with Down syndrome, with Shabang Inclusive Learning in collaboration with Mediapreview, Huddersfield, UK.
This film was made possible by generous funding from BBC Children in Need.
Down syndrome answers
The Canadian Down Syndrome Society found the most asked questions about Down syndrome on Google.
They asked 10 Canadians with Down syndrome to give their answers.
Click below to hear what they had to say, on the Candian Down Syndrome Society website:
Just like you
People with Down syndrome have an inherent right to be accepted and included as valued and equal members of the community.
The video ‘Just Like You’ is an example of how this is happening.
This video was jointly funded, produced and directed by two Kansas City, United States non-profit organisations.
About Down syndrome – FREE resources
We have created some resources to help you to learn a little more about Down syndrome.
A presentation to explain how Down syndrome occurs. Learn about cells, chromosomes and genes and what they do.
And an information pack covering topics relevant to people with Down syndrome, including diagnosis, early development, health, education, employment and much more.
Click here to access our resource hub:
More ways to get involved on 21 March
Theme for 2026
Learn how loneliness impacts people with Down syndrome and how we can fight this together.
Our global community
Connect with the Down syndrome community in your part of the world and learn how you can support local activities.
Lots Of Socks!
We want everyone to know that 21 March is World Down Syndrome Day. But how?
The answer is socks!! On 21 March, we wear our boldest, brightest, most eye-catching socks.
Sign up to hear from us.
Sign up for updates, including new resources and activities to help you mark this important day and make a difference for people with Down syndrome around the world.
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