CDKL5

CDKL5 is a is_associated_with::gene that provides instructions for making a is_associated_with::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 is_associated_with::kinase, which is an enzyme that changes the activity of other proteins by adding a cluster of is_associated_with::oxygen and is_associated_with::phosphorus atoms (a is_associated_with::phosphate group) at specific positions. Researchers have not determined which proteins are targeted by the CDKL5 protein.

Mutations
CDKL5 is sometimes associated with is_associated_with::Rett syndrome (though much less frequently than is_associated_with::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 (is_associated_with::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.

Mutations in the CDKL5 gene also cause a disorder called is_associated_with::X-linked infantile spasm syndrome (ISSX) or is_associated_with::West syndrome. Like the early-onset seizure variant of Rett syndrome, X-linked infantile spasm syndrome is characterized by recurrent seizures that begin in infancy. Children with this condition also have severe to profound intellectual disability and may have other brain abnormalities. The CDKL5 mutations responsible for X-linked infantile spasm syndrome lead to the production of an abnormally short, nonfunctional version of the CDKL5 protein. It remains uncertain how these defects cause seizures and intellectual disability.

Location
The CDKL5 gene is located on the short (p) arm of the X chromosome at position 22. More precisely, the CDKL5 gene is located from base pair 18,443,724 to base pair 18,671,748 on the X chromosome.