What is CDKL5?

CDKL5 stands for “cyclin-dependent kinase-like 5”.     







CDKL5 is a rare x-linked neurodevelopmental disorder.

Mutations in the CDKL5 gene can cause a disorder known as X-linked infantile spasm syndrome, which is characterized by recurrent seizures called infantile spasms that begin in the first year of life. Children with this condition also have intellectual disability. X-linked infantile spasm syndrome caused by CDKL5 gene mutations occurs more often in females, but it has been identified in a small number of males.

Girls with CDKL5 gene mutations have many of the features of classic Rett syndrome. However, unlike girls with classic Rett syndrome, they also develop recurrent seizures beginning in infancy. Although this condition was previously described as an atypical form of Rett syndrome (often called the early-onset seizure variant), it is now usually considered to be a separate condition.

CDKL5 disorder presents as a broad constellation of symptoms, one or more of the symptoms listed below may be present:

  • Seizure disorder
  • Limited or absent speech
  • Hypotonia
  • Lack of or poor eye contact 
  • Gastrointestinal difficulties
  • Limited or absent hand skills
  • Hand wringing movements
  • Autistic‐like tendencies
  • Scoliosis
  • Respiratory dysfunctions
  • Impaired sleep patterns
  • Cortical Visual Impairment (CVI)
  • Eating/drinking challenges  
  • Dysfunctions of the autonomous nervous system


What is the normal function of the CDKL5 gene?

The CDKL5 gene provides instructions for making a protein that is essential for normal brain development and function. The CDKL5 protein acts as a kinase, which is an enzyme that changes the activity of other proteins by adding a cluster of oxygen and phosphorus atoms (a phosphate group) at specific positions. One of the proteins targeted by the CDKL5 protein is MeCP2, which is produced from the MECP2 gene. The MeCP2 protein plays important roles in the function of nerve cells (neurons) and other brain cells and in the maintenance of connections (synapses) between neurons. Researchers have not determined which other proteins are targeted by the CDKL5 protein.


Where is the CDKL5 gene located?

Cytogenetic Location: Xp22







The CDKL5 gene is located on the short (p) arm of the X chromosome at position 22.

Reference:  Genetics Home Reference - http://ghr.nlm.nih.gov/gene/CDKL5#genefamilies