CDKL5 is a rare X-linked genetic disorder with early onset, difficult to control, resulting in seizures and severe neurodevelopmental impairment. CDKL5 is classified as a rare disease, but more and more children, and indeed adults, are being diagnosed with it.

The CDKL5 gene provides instructions for making a protein essential for normal brain development. Although little is known about the protein's function, it may play a role in regulating the activity of other genes, including the MECP2 gene (or Rett Syndrome).

The CDKL5 protein acts as a kinase, an enzyme that modifies the activity of other proteins by adding oxygen and phosphate atoms (a phosphate group) at certain positions. Researchers have yet to determine which proteins are targeted by the CDKL5 protein.

Most children affected by CDKL5 suffer from seizures that begin in the first few months of life. Many are unable to walk, talk or eat on their own, and many are wheelchair-bound and dependent on others for everything. Many also suffer from scoliosis, visual impairment, sensory issues and various gastrointestinal difficulties. As time passes, there may be other symptoms that play a role in this condition.