Children's Hospital Colorado

CDKL5 Deficiency Disorder (CDD)

What is CDKL5 deficiency disorder (CDD)?

CDD is a neurological and developmental disorder that affects boys and girls. Symptoms of CDD usually begin in infancy with repeated seizures (epilepsy), often in the second month of life. Children with CDD often have a special type of epilepsy called spasms that are difficult to treat with medicine. They also have delayed development, intellectual disability and difficulty walking and sitting. Many children have difficulty seeing, a condition called cortical visual impairment.

What causes CDD?

CDD involves a change or misspelling in a gene called the CDKL5 gene, which occurs on the X chromosome. Even though this is a genetic disorder, the change on the gene is new to the patient and not inherited from parents. In other words, a new spelling mistake happened around the time the egg and sperm came together. This is not caused by something the parents did or didn't do.

Who gets CDD?

CDD syndrome is a genetic disorder. It happens in 1 out of 41,000 births. It affects boys and girls.

What are the signs and symptoms of CDD?

Children have developmental delays, intellectual disability, difficulty with walking, talking, sitting and using their hands. Children often have difficulty seeing, a condition called cortical visual impairment.

What tests are used to diagnose CDD?

Since the signs and symptoms of CDD are common to many disorders, a blood test is needed for a diagnosis by checking for a genetic change in the CDKL5 gene on the X chromosome.

Your child’s doctor will look for the following symptoms to help make a diagnosis:

  • Lack of purposeful hand movements
  • Lack of speech
  • Balance and coordination problems (including the inability to sit or walk in many cases)
  • Intellectual and developmental disabilities
  • Cortical visual impairment
  • Reflux, constipation, difficulty swallowing and breathing problems
  • Abnormal movements of the hands or legs that can interfere with purposeful movement
  • Epilepsy that is difficult to treat, known as refractory epilepsy

How is CDD treated?

Because of its genetic nature, there is no cure for CDD at this time. At Children’s Hospital Colorado, our treatments are designed to help alleviate your child’s symptoms and to create the best possible quality of life. We see people of all ages for CDD in our Rett Clinic.

Some treatment approaches include medications to address possible seizures, gastroesophageal reflux, sleep, movement problems, constipation and breathing problems.

Feeding problems may also occur, requiring some children to need supplemental food from a feeding tube. Scoliosis (a curved spine) may also require orthopedic interventions like braces or surgeries.

Physical, occupational and speech therapy is also used to address motor, communication, sleep and behavioral difficulties. Although no cure is available, these supportive treatments help most children adapt to the symptoms of CDD.

Why choose us for the treatment of CDD?

Our team has developed a wealth of experience and knowledge about CDD, and we’re recognized as national and international leaders in the field through our published research. We strive to develop and provide the most up-to-date care based on research and care guidelines. We participate in the latest clinical trials.

Our sub-specialty providers and therapists come together to evaluate and develop a treatment plan that is tailored to your child’s specific needs. Because so many specialties are housed under the same roof at Children’s Colorado, we can provide all the care that children with Rett syndrome need.

Contact us

To make an appointment at the Rett Clinic, families and providers can contact the Rett Clinic at 720-777-4363 or email