CDKL5

CDKL5 is a gene that provides instructions for making a protein called cyclin-dependent kinase-like 5 also known as serine/threonine kinase 9 (STK9) 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. 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. Researchers have not determined which proteins are targeted by the CDKL5 protein.

Mutations

CDKL5 is sometimes associated with Rett syndrome (though much less frequently than MECP2). At least 10 mutations in the CDKL5 gene have been identified in girls with an atypical form of Rett syndrome known as the early-onset seizure variant. While CDKL5 is primarily associated with girls, it has been seen in boys as well. This disorder includes many of the features of classic Rett syndrome (including developmental problems, loss of language skills, and repeated hand wringing or hand washing movements), but also causes recurrent seizures beginning in infancy. Some CDKL5 mutations change a single protein building block (amino acid) in a region of the CDKL5 protein that is critical for its kinase function. Other mutations lead to the production of an abnormally short, nonfunctional version of the protein. Researchers are working to determine how these changes result in seizures and the characteristic features of Rett syndrome in affected children.