CDKL5 syndrome


The CDKL5 syndrome is a rare genetic disorder that causes an impaired brain development. It is caused by a mistake in the hereditary material. Worldwide, 500 people are known to have this condition.


The CDKL5 gene behaves like a kinase and influences the protein that is important for normal brain development.



A kinase is a type of enzyme that adds phosphates to other molecules, such as sugars or proteins, in the human cell. This can cause other molecules in the cell to become active or inactive. A kinase consumes kinetic energy in this catalytic reaction, hence the name kinase. See also here.


Another name for this condition is serine / threonine kinase 9 (STK9).



Children with this condition do not develop normally. The gene is on the X chromosome of which women have two and men one. As a result, the disorder is more common in girls than in boys.


The condition usually manifests itself by epileptic seizures from the first months of life and manifests itself in a delayed development of the child.


Characteristics vary per person

  • Epileptic seizures in the first months of life,
  • Different forms of epilepsy; usually with myoclonic shocks (individual or series of shocks that suddenly occur in the muscles, usually in the arms and sometimes in the legs),
  • Delayed development,
  • Limited or absent speech,
  • Low / poor muscle tone; the children are weak when they are lifted,
  • Later, more spasticity and stiffness occurs,
  • Infantile spasms (in about 50% of cases),
  • The head is too small (microcephaly) in about 50% of cases. Often the head circumference at birth is normal, but the head grows less quickly than it should,
  • Hand wringing movements, hand wash movements, very limited hand function,
  • Hypersensitivity to touch,
  • Lack of or poor eye contact,
  • Swallowing problems,
  • Gastroesophageal reflux; backflow of stomach contents,
  • Constipation or bowel movement too slow,
  • Irregularities in breathing such as hyperventilation,
  • Teeth grinding,
  • Laughing or crying for no reason,
  • Autistic traits; the children seem to live in their own world,
  • Scoliosis, lateral curvature of the spine,
  • Cortical / cerebral visual disorder (CVI), also known as cortical blindness,
  • Apraxia; not knowing how to perform an action,
  • Problems with eating / drinking,
  • Sleeping problem, often awake,
  • Sidelong glance,
  • Crossed or stretched legs