GENETIC POLYMORPHISM IN DNA BASE EXCISION REPAIR GENE XRCC1 AMONG MEDICAL RADIATION WORKERS

DNA damage can be caused by endogenous and exogenous factors.
The main endogenous factor is Reactive Oxygen Species (ROS), whereas exogenous factors are
environmental factors: ultra violet rays, ionizing radiation and chemicals. One of damaged DNA repair
pathways, base excision repair system (BER), plays an important role to maintain DNA integrity, prevent
cancer and DNA damage. BER is involved in the repairement of oxidized bases and single strand breaks
DNA after exposure by ROS, including ionizing radiation. X-rays Repair Cross-Complementing Group 1
(XRCC1) is a gene that plays an important role in BER and DNA repair both single strand break and double
strand breaks. Individuals with XRCC1 exon 10 (Arg399Gln) gene polymorphisms and carrying 399Gln
allele variants have a greater risk of DNA damage than their wildtype, 399Arg. This study was aimed to
examine the genotype frequencies of single nucleotide polymorphisms (SNPs) of XRCC1 exon 10 among
medical radiation workers. This study involved 77 samples from hospitals in Indonesia. Genotyping of
XRCC1 exon 10 gene polymorphism was performed using PCR-RFLP. Individuals with a XRCC1 399Gln (A
allele) had a lower frequency than wildtype of 399Arg (0.39 vs. 0.61). The results indicated that 39% of
medical radiation workers had a risk of repair efficiency of DNA damage and might influence an individual's risk of cancer. Ionizing radiation induces many types of damage to DNA, requiring multiple repair pathways
to restore genomics integrity. Other important genes, especially for DNA double-strand break repair, might
also play a role and should be further investigated. Polymorphisms leading to inefficient DNA repair might
also be associated with late reactions to radiotherapy.