International CdLS Awareness Day2026 · Date · History · Messages
The CdLS Foundation says International CdLS Awareness Day is observed on the second Saturday in May each year and lists the 2026 edition for 9 May.
About International CdLS Awareness Day
International CdLS Awareness Day is observed on the second Saturday in May. The CdLS Foundation uses the day to raise awareness of Cornelia de Lange syndrome (CdLS) and the people and families affected by it.
CdLS is a genetic developmental disorder whose features and severity can vary widely. Awareness material should therefore avoid assuming that every person with CdLS has the same appearance, abilities, medical needs or life experience.
Why International CdLS Awareness Day matters
The day can help people learn from reliable medical and family-support sources, recognize the diversity of people living with CdLS and connect families with established support organizations.
Awareness should emphasize dignity and accurate information rather than diagnosing someone from appearance, photographs or a short list of traits.
History of International CdLS Awareness Day
The CdLS Foundation says the first CdLS Awareness Day was observed in 1989, when Foundation staff organized an international yard sale to raise awareness.
The Foundation now identifies International CdLS Awareness Day as the second Saturday in May each year.
The Foundation’s 2026 event calendar places the observance on May 9, 2026.
How the observance developed
This timeline uses documented milestones from reviewed sources. Missing stages are left out rather than guessed.
CdLS Foundation staff
The Foundation history says staff organized the first CdLS Awareness Day activity in 1989.
CdLS Foundation
The Foundation’s own history and current awareness pages identify the Foundation with the observance.
First documented observance
The CdLS Foundation history identifies 1989 as the first CdLS Awareness Day.
CdLS Foundation
The CdLS Foundation currently publishes the recurring observance and participation information.
What the evidence establishes
Confirmed institutional roles and milestones are shown first. Details that could not be established from the reviewed sources are listed separately below.
5 fields not established in reviewed sources
Also known as
Cornelia De Lange Syndrome Awareness Day
How to Observe International CdLS Awareness Day
Share information from the CdLS Foundation or established medical genetics resources rather than symptom checklists presented as diagnosis.
Support fundraising or community events organized with appropriate consent and privacy protections.
When discussing a child or adult with CdLS, avoid sharing health, education or family information without permission.
Questions about diagnosis, treatment or genetic testing belong with qualified health and genetics professionals who can consider the individual person.
International CdLS Awareness Day Facts
The documented calendar date for International CdLS Awareness Day is the second Saturday in May.
The CdLS Foundation traces the first CdLS Awareness Day to 1989.
CdLS is a genetic developmental disorder.
Features and severity can vary widely from person to person.
An awareness page cannot diagnose CdLS from appearance, symptoms or photographs.
International CdLS Awareness Day Messages
May CdLS Awareness Day encourage learning without assumptions and support without stigma.
Here’s to awareness that sees the whole person, not a diagnosis alone.
Topic and context
What this page does not assume
- Keep the source-defined country, community, organizer or institutional scope; do not silently broaden it.
- Do not treat the title alone as proof of government recognition or public-holiday status.
- Do not add a creator, founding story or origin claim unless the supporting evidence establishes it.
- Health Information Not Medical Advice.
Evidence & sources
Sources used across the guide are gathered here. Labels show how each source supports the page, and contextual references are kept separate from primary evidence.
MedlinePlus Genetics — CdLS medical reference
CdLS Foundation — 2026 event page
CdLS Foundation — Our History
CdLS Foundation — Raise Awareness
CdLS Foundation — 2026 International CdLS Awareness Day (opens in a new tab)
First Party Health Charity
CdLS Foundation — Our History (opens in a new tab)
First Party Health Charity
CdLS Foundation — Raise Awareness (opens in a new tab)
First Party Health Charity
MedlinePlus Genetics — Cornelia de Lange syndrome (opens in a new tab)
Government Medical Reference
Understand it, compare it, then explore further
Start with the most common factual questions, then compare closely related observances and explore useful connections.
Frequently asked questions
When is International CdLS Awareness Day?
Second Saturday in May; 9 May 2026 The documented recurrence rule is: Second Saturday in May.
Does International CdLS Awareness Day fall on the same date every year?
It follows a recurring calendar rule, so the Gregorian date can change from year to year.
Is International CdLS Awareness Day an official public holiday?
The reviewed sources verify it within this scope: International / CdLS Foundation awareness observance. That recognition does not by itself make it a statutory public holiday; the site only makes public-holiday claims when reliable evidence explicitly does so.
Who established or recognizes International CdLS Awareness Day?
The reviewed sources identify CdLS Foundation as the proclaiming or establishing body. The proposer or originator is recorded separately as CdLS Foundation staff. Current facilitation or coordination is recorded as CdLS Foundation.
Is International CdLS Awareness Day international or country-specific?
The documented scope is international or global: International / CdLS Foundation awareness observance. That does not mean every country treats the date as a public holiday or observes it in the same way.
How is this page verified?
The factual information is checked against reviewed sources, including the date pattern, scope and institutional history. This page was checked on 2026-09-27.
When is International CdLS Awareness Day?
It is observed on the second Saturday in May.
When was the first CdLS Awareness Day?
The CdLS Foundation says the first observance was in 1989.
What is CdLS?
Cornelia de Lange syndrome is a genetic developmental disorder with features that can vary widely in type and severity.
Can an awareness guide diagnose CdLS?
No. Diagnosis and individual medical questions require qualified health and genetics professionals.
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A/RES/59/26