What is CDKL5?

CDKL5 is a rare X-linked genetic disorder that results in early onset, difficult to control seizures, and severe neuro-developmental impairment. CDKL5 is classed as rare disease however, more and more children and indeed adults are being diagnosed every day.

The CDKL5 gene provides instructions for making a protein that is 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, which is an enzyme that changes the activity of other proteins by adding oxygen and phosphate atoms (a phosphate group) at specific positions. Researchers have not yet determined 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. Most cannot walk, talk or feed themselves, and many are confined to wheelchairs, dependent on others for everything. Many also suffer with scoliosis, visual impairment, sensory issues and various gastrointestinal difficulties. As time has gone on it appears that there might be other symptoms that play a role in the condition.

This is the current list of symptoms, however it is important to note that not every child will have what is listed, and therefore appears to be a wide spectrum in terms of the severity of some children, from moderately affected to profoundly affected.

  • Epileptic seizures starting in the first 8 months of life.
  • Infantile spasms (in about 50%)
  • Many different types of epilepsy usually including myoclonic jerks
  • Hand stereotypies in the form of hand clapping, tapping, movements or mouthing
  • Marked developmental delay
  • Limited or absent speech
  • Hypersensitivity to touch, for example dislike of hair brushing
  • Lack of eye contact or poor eye contact, but may have intensive eye interaction
  • Gastro‐esophageal reflux, and other severe gastrointestinal problems such as low gut motility
  • Constipation
  • Small, cold feet
  • Breathing irregularities such as hyperventilation
  • Grinding of the teeth
  • Episodes of laughing or crying for what appears to be no reason
  • Low/Poor muscle tone
  • Very limited hand skills
  • Some autistic‐like tendencies
  • Scoliosis
  • Cortical Visual Impairment (CVI), aka “cortical blindness”
  • Apraxia
  • Eating/drinking challenges, such as refusal to eat and drink, as well as giving up altogether
  • Interruptive sleep
  • Characteristics such as a sideways glance, and habit of crossing legs