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POLE
DNA polymerase epsilon, catalytic subunit
The POLE gene provides instructions for making a crucial subunit of DNA polymerase epsilon, an enzyme vital for accurate DNA replication and repair processes within cells. The POLE gene is fundamental to maintaining genomic stability by encoding a key component of DNA polymerase epsilon.
POLE is located on the long (q) arm of chromosome 12, at band 12q24.33. Arm ratio per GRCh38 - banding schematic.
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Overview
The POLE gene, officially known as 'DNA polymerase epsilon, catalytic subunit', provides the genetic blueprint for the catalytic subunit of the DNA polymerase epsilon (Pol ε) enzyme. Within eukaryotic cells, Pol ε operates as a central part of the machinery responsible for DNA replication and repair. Its primary function involves synthesising new DNA strands with high precision, which is critical for preventing the introduction of errors or undesired changes into our genetic material.
Errors that occur during DNA replication or repair can build up over time, potentially leading to cellular dysfunction or various health conditions. Consequently, the accurate operation of the POLE gene and the enzyme it produces is essential for sustaining genomic stability and overall cellular well-being. Dysregulation or pathogenic variants within the POLE gene are linked to an increased susceptibility to certain inherited conditions, as its normal role is integral to preventing DNA damage and maintaining healthy cell cycles.
What the gene does
The protein encoded by the POLE gene serves as the catalytic subunit of DNA polymerase epsilon (Pol ε). This enzyme is actively involved in two vital cellular activities: chromosomal DNA replication and DNA repair. Specifically, it plays a role in pathways such as nucleotide excision repair and base excision repair [PMID:33610260]. During DNA replication, Pol ε functions as the leading strand polymerase, ensuring efficient and highly accurate synthesis of new DNA strands. This precise synthesis is paramount for preventing the introduction of mutations during cell division [PMID:24632360].
An important aspect of Pol ε's activity, facilitated by the POLE protein, is its proofreading capability. If an incorrect nucleotide is incorporated during DNA synthesis, Pol ε can detect and remove this error, thereby maintaining the fidelity of the DNA sequence [PMID:26760572]. This proofreading mechanism significantly lowers the rate of spontaneous mutations. Beyond replication, Pol ε also participates in DNA damage response pathways, helping to mend various types of DNA lesions and further safeguarding the genome's integrity. Its diverse functions highlight its importance in preventing genetic instability and the development of related diseases.
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Chromosome location
The POLE gene is situated on chromosome 12. Its precise location is designated as 12q24.33, which refers to the long arm (q) of chromosome 12, at band 24.33. This specific address indicates its position within the human genome.
Protein structure
The POLE protein is a substantial enzyme, comprising 2286 amino acids. Its structural organisation includes several distinct functional domains. Two primary disordered regions are found at its amino-terminal end, spanning amino acids 1-30 and 1939-1969 respectively. Towards the carboxyl-terminal end, the protein features a CysA-type (Zinc finger) domain from amino acids 2158-2190, and a CysB motif located between amino acids 2221-2238. These domains jointly contribute to the protein's catalytic activity and its interactions with DNA and other crucial cellular proteins.
Key variants
Variants within the POLE gene can lead to alterations in the structure and function of the DNA polymerase epsilon enzyme. These genetic changes may include single nucleotide substitutions, as well as larger insertions or deletions within the gene's sequence. Pathogenic variants often disrupt the enzyme's capacity to accurately synthesise and proofread DNA. This impairment results in a higher frequency of genetic errors or mutations. Such an increase in mutational burden can contribute to genomic instability, a characteristic feature of various inherited conditions. The inheritance pattern for conditions linked to POLE is autosomal dominant, meaning that inheriting just one altered copy of the gene is sufficient to increase a person's risk.
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.1270C>G | p.Leu424Val | Pathogenic | ★★☆☆ | Colorectal cancer, susceptibility to, 12 |
c.1686+32C>G | - | Pathogenic/Likely pathogenic | ★★☆☆ | Intrauterine growth retardation, metaphyseal dysplasia, adrenal hypoplasia congenita, genital anomalies, and immunodeficiency |
c.51dup | p.Glu18fs | Pathogenic | ★★☆☆ | Facial dysmorphism-immunodeficiency-livedo-short stature syndrome |
c.5678+1G>T | - | Pathogenic | ★★☆☆ | not provided |
c.5811+1G>A | - | Pathogenic/Likely pathogenic | ★★☆☆ | not provided |
g.(?_132632305)_(132632805_?)del | - | Pathogenic | ★☆☆☆ | not provided |
g.(?_132660959)_(132661174_?)del | - | Pathogenic | ★☆☆☆ | not provided |
c.1106G>A | p.Trp369Ter | Pathogenic | ★☆☆☆ | not provided |
c.2402_2403insG | p.Tyr801Ter | Pathogenic | ★☆☆☆ | not provided |
c.2756_2759del | p.Leu919fs | Pathogenic | ★☆☆☆ | not provided |
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 the POLE gene are associated with an increased genetic predisposition to certain inherited health conditions. The primary condition linked to alterations in the POLE gene is Polymerase Proofreading-associated Polyposis. This condition is inherited in an autosomal dominant manner and is characterised by an elevated risk for developing multiple polyps in the colon, which can increase the likelihood of developing colorectal cancer.
- Polymerase proofreading-associated polyposis Dedicated page coming soon
Inheritance pattern
Conditions caused by pathogenic POLE variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
The POLE gene is recognised by the UK's National Health Service (NHS) Genomic Medicine Service. It is listed on several NHS England National Genomic Test Directory panels, underscoring its clinical importance for diagnostic testing. Relevant panels include 'Adult solid tumours cancer susceptibility', 'Colorectal cancer pertinent cancer susceptibility', and 'Inherited polyposis and early onset colorectal cancer - germline testing'. All these panels are categorised as green, indicating that genetic testing for POLE is routinely available through the NHS.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
General healthy lifestyle behaviours may play a role in overall health outcomes for individuals with genetic predispositions. For example, maintaining a balanced diet, rich in fruits, vegetables, and whole grains while limiting processed foods, has generally been associated with a reduced risk of various chronic diseases. Regularly engaging in physical activity, maintaining a healthy weight, and avoiding smoking and excessive alcohol intake are also widely recognised as beneficial for general well-being. These broad lifestyle recommendations are often relevant for the general population and may support cellular health and immune function. Specific lifestyle interventions for individuals with POLE gene variants should be discussed with a healthcare professional.
Supplement considerations
There is no conclusive scientific evidence to suggest that specific dietary supplements can prevent or treat conditions associated with POLE gene variants. While some supplements are promoted for general health, their efficacy in preventing polyposis or cancer in individuals with genetic predispositions has not been established. Patients considering any supplements should consult with their healthcare provider to discuss potential benefits, risks, and interactions with other medications. Nutritional needs should ideally be met through a balanced diet.
Frequently asked questions
What is the main function of the POLE gene?
The POLE gene encodes a critical part of DNA polymerase epsilon, an enzyme essential for accurate DNA replication and repair, particularly proofreading newly synthesised DNA to correct errors.
How is Polymerase Proofreading-associated Polyposis inherited?
Polymerase Proofreading-associated Polyposis is inherited in an autosomal dominant manner, meaning that only one altered copy of the POLE gene is sufficient to increase an individual's risk for the condition.
Are POLE gene variants relevant for cancer screening?
Yes, variants in the POLE gene are associated with an increased risk for certain cancers, particularly colorectal cancer, and are included in NHS England's genetic testing panels for cancer susceptibility.
Can lifestyle changes prevent conditions linked to POLE gene variants?
While general healthy lifestyle choices are beneficial for overall well-being, there is no direct evidence that specific lifestyle changes can prevent conditions linked to POLE gene variants. Personalised advice should come from a healthcare provider.
Where is the POLE gene located?
The POLE gene is located on chromosome 12, specifically at position 12q24.33 within the human genome.