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XPD polymorphisms: effects on DNA repair proficiency

R M Lunn1, K J Helzlsouer, R Parshad

  • 1Laboratory of Computational Biology and Risk Analysis, National Institute of Environmental Health Sciences, National Institutes of Health, MD C3-03, PO Box 12233, Research Triangle Park, NC 27709, USA.

Carcinogenesis
|April 7, 2000
PubMed

Insights

The XPD gene

Area of Science:

  • Genetics
  • Molecular Biology
  • DNA Repair Mechanisms

Background:

  • XPD is a DNA helicase crucial for transcription and nucleotide excision repair.
  • XPD mutations impair DNA repair, increasing UV sensitivity and skin cancer risk.
  • The functional impact of common XPD gene polymorphisms on DNA repair remains unclear.

Purpose of the Study:

  • To investigate the association between XPD gene polymorphisms at codons 312 and 751 and DNA repair proficiency.
  • To determine if specific XPD genotypes influence the repair of X-ray-induced DNA damage.

Main Methods:

  • Genotyping of XPD codons 312 and 751 using PCR-RFLP in 31 women.
  • Assessment of DNA repair proficiency via a cytogenetic assay measuring X-ray-induced chromatid aberrations.
  • Scoring of chromatid aberrations per 100 metaphase cells after a repair incubation period.

Main Results:

  • The XPD Lys/Lys genotype at codon 751 was linked to a significantly higher number of chromatid aberrations (132/100 cells) compared to the 751Gln allele (34/100 cells).
  • Individuals with the Lys/Lys751 genotype had an increased risk (OR=7.2) of sub-optimal DNA repair, defined as >60 chromatid breaks/gaps.
  • The XPD Asp312Asn polymorphism did not show a significant effect on DNA repair proficiency.

Conclusions:

  • The XPD Lys751 allele may be associated with reduced DNA repair capacity for X-ray-induced damage.
  • This suggests that common XPD polymorphisms can influence DNA repair efficiency, potentially impacting cancer risk.
  • Further research is needed to fully elucidate the role of XPD variants in DNA repair and disease susceptibility.

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