The gene
CDKL5 is a gene that helps the brain develop and work properly.
This page has not yet been reviewed by our Scientific and Medical Advisory Committee. Content is written by parent volunteers and may not reflect current medical guidelines.
About CDKL5
A condition you may never have heard of, until someone you love is diagnosed.
CDKL5 Deficiency Disorder is a rare genetic condition that affects brain development and can cause seizures from the first weeks or months of life. This page is a place for Australian families to start getting their bearings.
The condition
CDKL5 Deficiency Disorder, or CDD, happens when this gene does not work as expected.
The journey
Children can experience early seizures, developmental delays, vision challenges, and complex care needs.
What is CDKL5?
CDKL5 is a gene that helps the brain develop and work properly. When this gene has a change, sometimes called a mutation or variant, it can cause a condition called CDKL5 Deficiency Disorder, or CDD.
CDD is a rare genetic condition. It affects how the brain develops and can cause seizures that start early in life, often in the first weeks or months.
CDKL5 the gene, CDD the condition
You might hear both terms used. Here is the simplest way to think about it:
CDKL5
The gene
CDD
The condition that can occur when the gene does not work as expected
Some older resources may refer to it as “CDKL5 disorder” or “CDKL5 epilepsy.” The internationally recognised name today is CDKL5 Deficiency Disorder.
How does CDD affect children?
Every child with CDD is different, and no two journeys look alike.
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Seizures
Often the first sign, sometimes starting in the first weeks of life. Seizures can be frequent and difficult to control.
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Developmental differences
Most children have significant delays in sitting, walking, and communicating.
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Cortical visual impairment
Many children have difficulty processing what they see, even though their eyes may be healthy.
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Movement and muscle tone
Some children have low muscle tone and/or involuntary hand movements.
There is no cure for CDD today. But therapies, medications, and the right support can meaningfully improve quality of life, and research is moving faster than it ever has.
Estimated prevalence
1 in 40,000 to 1 in 60,000
live births worldwide. As awareness grows, more people are being diagnosed who were previously undiagnosed or misdiagnosed.
All genders
CDD affects all genders. Boys can be affected too, and sometimes more severely.
What CDKL5 Australia does
CDKL5 Australia is a community association, run by Australian families living with CDD.
Learn more about us-
Connect families
So no one navigates this journey alone.
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Provide plain-language information
Written by parents and reviewed by clinicians where possible.
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Signpost research and clinical trials
So families can make informed choices.
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Be an Australian point of contact
For hospitals, clinicians, researchers and families.
We work closely with global research partners.
You’re not the first family. And you won’t be alone.
If you’ve just had a diagnosis, or you’re trying to make sense of one, please reach out. We’ll help connect you with families, clinicians, resources and research pathways.