Kleefstra Syndrome UK Christmas Jumper Day – 17th December

Wear a jumper. Raise awareness. Support families.

Join us on the 17th December for our first ever Kleefstra Syndrome UK Christmas Jumper Day.
We’re inviting schools, workplaces, clubs and families across the UK to wear a festive jumper, donate 50p (or more!), and help raise awareness of Kleefstra Syndrome.

Why the 17th December?

KS arises from a change on chromosome 9 at 9q34.3. The 9th month is September, and the 17th letter of the alphabet is Q— so the 17th of September has always been our annual date to unite and make our voices heard. So it makes sense for the 17th of December to become our festive symbol of hope and support for our community. By coming together on the 17th December, we not only bring festive fun — we shine a light on the lived experience of children and adults with KS.

What is Kleefstra Syndrome (KS)?

Kleefstra Syndrome is a rare genetic condition caused by an alteration in chromosome 9. It often leads to developmental delays, low muscle tone, differences in communication and learning, and a range of other health & support needs.

For families across the UK, KS means navigating the usual joys of childhood alongside extra challenges — for the child with KS, their siblings, and their whole family network.

How can you get involved?

• Wear your jumper: Whether it’s sparkly, silly, homemade or classic — don’t hold back.

• Optional 50p donation to Kleefstra Syndrome UK (or more if you can) — every bit helps us continue family support and awareness work.

• Tell your community: Share the message with friends, schools, workplaces, social media. Use the hashtags #KSChristmasJumperDay & #KleefstraSyndromeUK.

• Take a photo and share it — help us build momentum and show solidarity across the UK.

Why your support matters

Kleefstra Syndrome UK is a registered charity (Charity Commission) and receives no statutory funding — we rely entirely on the generosity of families, friends and supporters. By joining our Jumper Day, you’re not just taking part in a fun tradition — you’re helping our charity to continue offering specialist guidance, family-to-family support and raising awareness so that children and adults with KS don’t get left behind.

Schools, workplaces & organisations — we’d love you!

This is a fantastic opportunity for schools, nurseries, youth groups, and businesses to show support.

• Invite pupils or colleagues to wear a Christmas jumper on the 17th December.

• Ask for an optional donation (suggested 50p).

• Use our letter template, poster/flyer and social-media assets (downloadable below) to spread the word.

• Let us know you’re participating — we’d love to feature you and celebrate your support.

Download your kit

Below you’ll find everything you need to make 2025’s Kleefstra Christmas Jumper Day a success:

• Parent/guardian letter Word template to send to your school to ask for their support / participation on the 17th December – KS School Letter XmasJumperDay25

• A4 poster/flyer – Xmas Jumper PosterFlyer-2

• Fundraising hints and tips Fundraising Hints and Tips

Thank you

Your jumper. Your donation. Your voice.

Together we can raise awareness, spark conversations and make life better for children and families living with KS. Mark your calendar for the 17th December — we hope to see you in a Christmas jumper! Be sure to let us know if your school (or workplace of course!) is able to support our festive day so we can spread the word across our social media channels and help raise even more awareness! And of course, forwarding on your donations via our DONATE link is MUCH appreciated!

Contact & Support

If you have any questions, would like additional materials or want to let us know you’re joining in, please contact us at info@kleefstrasyndrome.org.