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PRKDC
protein kinase, DNA-activated, catalytic subunit
PRKDC is located on the long (q) arm of chromosome 8, at band 8q11.21. Arm ratio per GRCh38 - banding schematic.
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Overview
PRKDC (protein kinase, DNA-activated, catalytic subunit) is located on chromosome 8 and produces the DNA-PKcs protein, which acts as a molecular sensor and coordinator of DNA damage responses. Double-strand breaks occur naturally during normal cellular processes and can also arise from environmental exposures such as ionising radiation. The DNA-PKcs enzyme belongs to the phosphatidylinositol 3-kinase-related kinase family and plays an indispensable role in joining broken DNA ends back together. Without functional DNA-PKcs, cells struggle to repair these breaks efficiently, which can compromise immune system development and increase susceptibility to chromosomal instability. The gene's importance is reflected in its essential role during V(D)J recombination, the process that generates antibody and T-cell receptor diversity.
What the gene does
DNA-PKcs functions primarily as the catalytic core of the DNA-dependent protein kinase complex, which also includes the Ku70 and Ku80 proteins. When a double-strand break occurs, the Ku heterodimer rapidly binds to the broken DNA ends and recruits DNA-PKcs to the damage site. Once assembled, DNA-PKcs undergoes activation and phosphorylates numerous target proteins involved in DNA repair, cell cycle regulation, and damage signalling. The enzyme's kinase activity is essential for coordinating the non-homologous end joining pathway, which directly ligates broken DNA ends without requiring a complementary template. This repair mechanism is particularly important in non-dividing cells and during specific developmental processes. Beyond its repair functions, DNA-PKcs participates in telomere maintenance, helping to protect chromosome ends from being recognised as DNA breaks. The protein also contributes to the cellular response to replication stress and plays a role in maintaining overall genomic stability across cell divisions.
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Chromosome location
The PRKDC gene is positioned on the long arm of chromosome 8 at band q11.21. This chromosomal region contains multiple genes involved in cellular regulation and has been studied in the context of various genomic rearrangements. The precise number of exons and detailed transcript architecture for PRKDC have been characterised through genomic sequencing efforts, though specific structural features vary across different transcript isoforms.
Protein structure
Domain architecture has not been experimentally characterised in detail for this protein.
Key variants
Genetic variants in PRKDC range from common population polymorphisms to rare pathogenic changes that severely impair protein function. Variants that compromise DNA-PKcs catalytic activity or prevent proper assembly with the Ku proteins can lead to defective DNA repair. The spectrum of reported variants includes missense changes affecting critical functional regions, nonsense variants that truncate the protein, and splice-site alterations that disrupt normal gene expression. The clinical significance of specific variants depends on their impact on enzyme activity and the resulting capacity for double-strand break repair.
Sample of pathogenic variants
3 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.9185T>G | p.Leu3062Arg | Pathogenic | ★☆☆☆ | Severe combined immunodeficiency due to DNA-PKcs deficiency |
GRCh37/hg19 8q11.21(chr8:48730498-48829786)x1 | - | Pathogenic | - | not provided |
c.10721C>T | p.Ala3574Val | Pathogenic | - | Severe combined immunodeficiency due to DNA-PKcs deficiency |
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
Pathogenic variants in PRKDC have been associated with severe combined immunodeficiency, a condition characterised by profound defects in both T-cell and B-cell function. Individuals with complete loss of DNA-PKcs activity typically present with recurrent infections in infancy due to impaired lymphocyte development. The protein's role in V(D)J recombination means that its absence prevents normal maturation of immune cells. Additionally, some research has explored potential connections between reduced DNA-PKcs function and increased cellular sensitivity to radiation, though the clinical implications of partial loss-of-function remain an area of ongoing investigation.
No disease links recorded for this gene in our reference set.
UK clinical status
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the PRKDC gene do?
PRKDC provides instructions for making DNA-PKcs, an enzyme that repairs double-strand breaks in DNA through the non-homologous end joining pathway. This protein is essential for maintaining genome stability and enabling proper immune cell development.
How do PRKDC variants affect health?
Pathogenic variants that severely impair DNA-PKcs function can lead to immune deficiency due to disrupted lymphocyte maturation. The severity of health impact typically correlates with how much the variant reduces the protein's ability to coordinate DNA repair and support V(D)J recombination.
Is PRKDC testing available on the NHS?
PRKDC is not currently part of routine NHS genomic testing panels. Testing may be arranged through specialist immunology services when a primary immunodeficiency is suspected based on clinical presentation and family history.