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CDKL5
cyclin dependent kinase like 5
The CDKL5 gene provides instructions for a protein crucial for normal brain development and function, with variants in this gene linked to severe neurological conditions. The CDKL5 gene encodes a cyclin-dependent kinase-like 5 protein, which is highly active in the brain and plays a vital role in neuronal formation, growth, and signalling.
CDKL5 is located on the short (p) arm of chromosome X, at band Xp22.13. Arm ratio per GRCh38 - banding schematic.
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Overview
The CDKL5 gene, which stands for cyclin-dependent kinase like 5, provides the genetic blueprint for a protein found throughout the human body, with its highest activity concentrated in the brain. This gene is fundamental for proper brain development and function. Variants within the CDKL5 gene are primarily recognised for their association with CDKL5 deficiency disorder, a condition characterised by severe neurological symptoms.
Several versions, or isoforms, of the CDKL5 protein exist, differing in length and tissue distribution [PMID:31589304]. The protein functions as a kinase, an enzyme that modifies other proteins by adding a phosphate group, thereby altering their activity. This enzymatic action is thought to be critical for various cellular processes within the nervous system.
What the gene does
The protein produced from the CDKL5 gene acts as a kinase, an enzyme that regulates the activity of other proteins by attaching a phosphate group to them. This phosphorylation mechanism is critical for numerous cellular functions. Research indicates that the CDKL5 protein is predominantly active in the brain, where it is essential for several key processes related to neuronal health and function.
Specifically, the CDKL5 protein is involved in the formation, growth, and migration of nerve cells, known as neurons. It also plays a role in cell division and is implicated in the transmission of chemical signals across synapses, the connections between neurons. One potential target for phosphorylation by the CDKL5 protein is MeCP2, a protein encoded by the MECP2 gene, which is known to be important for neuronal function and the maintenance of synaptic connections. While MeCP2 is a suspected target, other proteins that interact with CDKL5 are still under investigation, highlighting the complexity of its regulatory roles in the brain [PMID:24177309].
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Chromosome location
The CDKL5 gene is situated on the short arm of the X chromosome at position Xp22.13. As an X-linked gene, its inheritance pattern means that conditions associated with CDKL5 often present differently in males and females. The gene provides instructions for making a protein that consists of 960 amino acids.
Protein structure
The CDKL5 protein is composed of 960 amino acids. Its structural organisation includes several key regions that contribute to its function as a kinase. A prominent Protein kinase domain is located between amino acids 13 and 297, which is responsible for the protein's enzymatic activity in phosphorylating other proteins. Additionally, the CDKL5 protein contains multiple Disordered regions. These include segments spanning amino acids 300-349, 382-566, 646-834, and 848-960. Disordered regions are flexible and often involved in protein-protein interactions and cellular signalling, allowing the protein to adopt different conformations and interact with various partners.
Key variants
Variants within the CDKL5 gene can lead to alterations in the structure and function of the CDKL5 protein. These genetic changes can range from single nucleotide substitutions to larger deletions or duplications. Pathogenic variants can impair the protein's ability to act as a kinase or affect its crucial roles in brain development and neuronal function. More than 150 different pathogenic variants in the CDKL5 gene have been identified as causes of CDKL5 deficiency disorder. Understanding these variants is key to comprehending the genetic basis of this severe neurological condition [PMID:22960682].
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.214G>A | p.Glu72Lys | Pathogenic | ★★★☆ | Juvenile retinoschisis |
c.119C>T | p.Ala40Val | Pathogenic | ★★★☆ | Developmental and epileptic encephalopathy, 2 |
c.1211_1212dup | p.Leu405fs | Pathogenic | ★★★☆ | not provided |
c.1247_1248del | p.Glu416fs | Pathogenic | ★★★☆ | not provided |
c.1311dup | p.Ser438fs | Pathogenic | ★★★☆ | Atypical Rett syndrome |
c.146-1G>A | - | Pathogenic | ★★★☆ | Developmental and epileptic encephalopathy, 2 |
c.2152G>A | p.Val718Met | Pathogenic | ★★★☆ | not provided |
c.215T>C | p.Ile72Thr | Pathogenic | ★★★☆ | Developmental and epileptic encephalopathy, 2 |
c.220G>T | p.Glu74Ter | Pathogenic | ★★★☆ | not provided |
c.2500C>T | p.Gln834Ter | Pathogenic | ★★★☆ | Developmental and epileptic encephalopathy, 2 |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Variants in the CDKL5 gene are predominantly associated with CDKL5 deficiency disorder, a rare and severe neurodevelopmental condition. This disorder is characterised by symptoms that typically begin in infancy, including recurrent seizures that are often difficult to control. Affected individuals frequently experience significant delays in various aspects of development, including severe intellectual disability. The condition is more commonly observed in females due to its X-linked inheritance pattern. Mutations in CDKL5 may also be linked to other forms of epilepsy, including West syndrome.
Inheritance pattern
Conditions caused by pathogenic CDKL5 variants typically follow x-linked inheritance.
X-linked recessive: sons of a carrier mother have a 50% chance of being affected. Daughters have a 50% chance of being carriers.
UK clinical status
CDKL5 is recognised by the UK National Health Service (NHS) Genomic Medicine Service and is included on several of its national testing panels, reflecting its clinical significance. It has a 'green' status on the Developmental Disorders Gene Panel (DDG2P), indicating strong evidence for gene-disease association. Furthermore, CDKL5 is part of the Early onset or syndromic epilepsy panel (R59), the Foetal anomalies panel (R21), and the Intellectual disability panel (R29), demonstrating its relevance in diagnosing and understanding a range of neurological and developmental conditions within the UK clinical setting.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Maintaining a healthy lifestyle, including a balanced diet and regular physical activity, is generally beneficial for overall health. For individuals with genetic conditions, lifestyle modifications are often considered part of a comprehensive management plan. While lifestyle choices do not alter the underlying genetic cause of conditions like CDKL5 deficiency disorder, they may help manage symptoms or improve general well-being. For example, some studies suggest that consistent sleep patterns and a supportive environment may contribute to better symptom management in individuals with neurological conditions. Any significant lifestyle changes should always be discussed with a healthcare professional.
Supplement considerations
Currently, there is no conclusive scientific evidence to suggest that specific dietary supplements can prevent or treat conditions associated with CDKL5 gene variants. While some nutrients are essential for brain health, relying on supplements to manage a complex genetic disorder is not recommended. For individuals considering supplements, it is crucial to consult with a healthcare provider or a registered dietitian. They can provide personalised advice, assess potential interactions with medications, and ensure that any supplement use is safe and appropriate, considering individual health needs.
Frequently asked questions
What is the primary function of the CDKL5 gene?
The CDKL5 gene provides instructions for making a protein that acts as a kinase, an enzyme crucial for normal brain development and function. It is involved in the formation, growth, migration of nerve cells, and the transmission of chemical signals between neurons.
What condition is most strongly associated with CDKL5 gene variants?
The CDKL5 gene is primarily associated with CDKL5 deficiency disorder, a severe neurodevelopmental condition characterised by early-onset seizures, significant developmental delays, and intellectual disability.
Is CDKL5 deficiency disorder more common in males or females?
CDKL5 deficiency disorder is more commonly observed in females due to its X-linked inheritance pattern, as the CDKL5 gene is located on the X chromosome.
Can lifestyle changes prevent CDKL5 deficiency disorder?
No, lifestyle changes cannot prevent CDKL5 deficiency disorder, as it is caused by genetic variants. However, a healthy lifestyle can contribute to general well-being and symptom management for individuals with the condition, and any changes should be discussed with a healthcare professional.
Is there a cure for CDKL5 deficiency disorder?
Currently, there is no cure for CDKL5 deficiency disorder. Treatment typically focuses on managing symptoms, such as seizures and developmental delays, through various therapies and medications to improve quality of life.
References
- Barbiero I, Valente D, Chandola C. CDKL5 localizes at the centrosome and midbody and is required for faithful cell division. Scientific reports. 2017. PMID: 28740074
- Hector RD, Kalscheuer VM, Hennig F. CDKL5 variants: Improving our understanding of a rare neurologic disorder. Neurology. Genetics. 2017. PMID: 29264392
- Hector RD, Dando O, Landsberger N. Characterisation of CDKL5 Transcript Isoforms in Human and Mouse. PloS one. 2016. PMID: 27315173
- Fehr S, Wilson M, Downs J. The CDKL5 disorder is an independent clinical entity associated with early-onset encephalopathy. European journal of human genetics : EJHG. 2013. PMID: 22872100
- Bahi-Buisson N, Bienvenu T. CDKL5-Related Disorders: From Clinical Description to Molecular Genetics. Molecular syndromology. 2012. PMID: 22670135
- Bahi-Buisson N, Villeneuve N, Caietta E. Recurrent mutations in the CDKL5 gene: genotype-phenotype relationships. American journal of medical genetics. Part A. 2012. PMID: 22678952
- Valli E, Trazzi S, Fuchs C. CDKL5, a novel MYCN-repressed gene, blocks cell cycle and promotes differentiation of neuronal cells. Biochimica et biophysica acta. 2012. PMID: 22921766