ERCC2 rs1799793: Asp312Asn Variant and DNA Repair
The rs1799793 missense variant (often studied alongside related nucleotide excision repair markers like rs2228526) is a common single nucleotide polymorphism located in the ERCC2 gene, altering codon 312 from aspartic acid to asparagine (Asp312Asn). The ERCC2 gene encodes the XPD helicase, an essential component of the cellular machinery responsible for repairing DNA lesions induced by ultraviolet radiation and chemical carcinogens. Scientific investigations have examined whether this variant subtly influences nucleotide excision repair efficiency, actinic skin changes, and susceptibility to certain malignancies, though clinical evidence for direct diagnostic utility remains limited.
What each genotype means
Typical DNA repair capacity
This genotype represents the most common version of the ERCC2 gene, often referred to as the Asp312 allele. Research suggests this version supports standard cellular nucleotide excision repair, which is the process used to clear UV-induced DNA damage. While this is the baseline profile, individual cancer risk is influenced by many factors, and you should continue to follow standard dermatological advice regarding sun protection.
This is the most common genotype in European populations, where the G allele is the major allele.
Varied DNA repair efficiency
This heterozygous genotype contains one copy of the common G allele and one copy of the A allele (Asn312). Some studies have observed associations between this genotype and altered DNA repair capacity or increased susceptibility to certain cancers, though findings are often inconsistent across different populations and cancer types. This variant does not indicate a disease state, but you should maintain consistent sun safety practices and discuss any specific health concerns with your physician.
Carried by a significant portion of the population, with the A allele occurring at a frequency of approximately 0.34 in Europeans.
Potential reduced repair capacity
This homozygous genotype consists of two copies of the A allele (Asn312). Some research indicates that this variant may be associated with a reduced capacity to clear UV-induced DNA damage compared to the GG genotype, potentially influencing long-term skin health. Because evidence is limited and results vary by ancestry, this genotype should be viewed as one of many factors in your overall health profile rather than a diagnostic indicator.
This is the least common genotype for this variant in European populations, occurring less frequently than the heterozygous or homozygous major genotypes.
Genetic Identity and Biological Architecture
The single nucleotide polymorphism known as Asp312Asn within the ERCC2 gene represents a single-base substitution that alters the amino acid sequence of the resulting protein product. Located on chromosome 19q13.3, ERCC2 encodes the xeroderma pigmentosum group D (XPD) protein, an integral ATP-dependent 5' to 3' DNA helicase subunit of the core general transcription factor IIH (TFIIH) complex. In genomic records, the ancestral G allele encodes an aspartic acid residue (Asp), whereas the alternative A allele directs the incorporation of an asparagine residue (Asn) at position 312 of the polypeptide chain. Because the variant changes an amino acid in a functional helicase domain, cellular researchers have long evaluated whether this subtle structural alteration influences how efficiently the TFIIH complex coordinates DNA unwinding or protein-protein interactions during active repair cycles.
Cellular Function: The Nucleotide Excision Repair Pathway
The primary role of the ERCC2/XPD protein is coordinating nucleotide excision repair (NER), a versatile and conserved cellular pathway that recognizes and removes bulky helix-distorting DNA damage. When skin or other tissues are exposed to solar ultraviolet (UV) radiation, harmful photo-products such as cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts form across adjacent pyrimidine bases. As detailed in resources like MedlinePlus Genetics ([MedlinePlus Genetics: ERCC2](https://medlineplus.gov/genetics/gene/ercc2/)), the TFIIH complex arrives at the lesion, where XPD unwinds the double helix to expose the damaged single-stranded segment so that structure-specific endonucleases can excise it. Severe loss-of-function pathogenic mutations in ERCC2 lead to rare monogenic disorders such as xeroderma pigmentosum group D and trichothiodystrophy, illustrating the absolute necessity of functional NER in preventing rapid mutagenesis and cellular senescence.
Research Evidence on UV Sensitivity and Health Outcomes
Unlike high-penetrance rare mutations that cause mendelian diseases, common polymorphic variations in ERCC2—such as Asp312Asn and its frequent partner Lys751Gln—act as modest, low-penetrance susceptibility traits ([PubMed Search: rs1799793](https://pubmed.ncbi.nlm.nih.gov/?term=rs1799793)). Epidemiological research has investigated whether individuals carrying the alternative Asn allele have slightly altered cellular capacities to clear UV-induced lesions, potentially influencing the risk of photo-aging phenotypes like actinic elastosis or common epithelial skin cancers. However, published findings across diverse case-control cohorts and genome-wide association studies (GWAS) show variable and conflicting results. While some studies suggest modest differences in repair kinetics, large-scale meta-analyses frequently report weak or null associations across unselected cohorts, classifying the current clinical evidence level as limited.
Population Distribution and Ancestral Patterns
The Asp312Asn allele frequencies vary significantly across different continental ancestries documented in reference databases such as the Genome Aggregation Database ([gnomAD Browser](https://gnomad.broadinstitute.org/)) and dbSNP ([NCBI dbSNP](https://www.ncbi.nlm.nih.gov/snp/)). In populations of European descent, the minor allele frequency is relatively common, typically ranging around 0.30 to 0.35. In contrast, the minor allele is observed at substantially lower frequencies in East Asian populations, where frequencies typically hover near 0.10. Because background allele frequencies diverge considerably across global groups, researchers must apply rigorous ancestry-matching to prevent false-positive statistical associations in genetic association studies.
Clinical Utility and Lifestyle Context
Carrying an alternative allele at the ERCC2 Asp312Asn locus is not a medical diagnosis and cannot predict whether an individual will develop UV-induced skin damage or any specific cancer. In clinical genetics, this common polymorphism is regarded as a benign background variant that does not alter standard medical recommendations. Standard dermatological guidance—such as using broad-spectrum sunscreen, seeking shade during peak solar hours, wearing protective clothing, and undergoing routine clinical skin checks—applies equally to all individuals regardless of their personal ERCC2 genotype. Consumers reviewing their raw personal genomics results should avoid modifying medical or lifestyle regimens based solely on this low-penetrance marker.
How common is this variant?
The minor alternative allele frequency is approximately 0.34 in European populations, whereas it occurs at a lower frequency of around 0.10 in East Asian populations according to gnomAD data.
Frequently asked questions
Does carrying an ERCC2 variant mean I have xeroderma pigmentosum?
No. Xeroderma pigmentosum is an extremely rare mendelian condition caused by severe, damaging mutations that disrupt the entire XPD helicase. Common polymorphisms like Asp312Asn are widely present in healthy global populations and do not cause xeroderma pigmentosum.
Can this genetic variant predict my personal risk of skin cancer?
No, this variant cannot reliably predict your individual risk of skin cancer. While researchers have studied statistical associations in population groups, environmental exposure, skin phototype, and lifestyle factors play far more decisive roles.
How does the ERCC2 gene protect cells from sunlight?
The ERCC2 gene codes for an essential subunit of the TFIIH protein complex known as XPD. This protein functions as a helicase that helps open and unwind strands of DNA so that bulky chemical damage caused by UV radiation can be clipped out and replaced with correct genetic letters.
Should I adjust my sun protection habits based on my genotype?
No, you should not modify standard sun safety practices based on this genotype. Established preventive measures, such as applying broad-spectrum sunscreen and avoiding severe sunburns, are uniformly recommended for all individuals regardless of their genetic test results.
Sources & further reading
Educational information only, last refreshed 9/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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