CDKL5 stands for cyclin-dependent kinase-like 5, a protein whose gene is located on the X chromosome. The CDKL5 gene provides instructions for making a protein that is essential in forming the connections for normal brain development, with mutations causing a deficiency in the protein level.
Most children affected by CDKL5 deficiency (about 90 percent of whom are girls) 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 problems, and gastrointestinal difficulties.
CDKL5 mutations have been found in children previously diagnosed with cerebral palsy and autism, among other conditions, and the resulting disorder had also been previously classified as an early onset seizure variant of Rett Syndrome but is now but it is now known to be an independent clinical entity caused by mutations in a distinct X-linked gene, and therefore a separate disorder with its own defined characteristics. Mutations in the gene are usually spontaneous ‘de novo’ occurrences, rather than inherited. There are more than 1,600 documented cases of CDKL5 Deficiency Disorder worldwide, with the number of identified patients increasing as genetic testing for the disorder becomes more common.