title: Impact of EXO1 polymorphism in susceptibility to colorectal cancer.
abstract: OBJECTIVE
  One candidate gene for colorectal cancer (CRC) susceptibility is exonuclease 1 (EXO1). It is a member of RAD2 nuclease family, which plays a major role in mismatch repair, DNA replication, and recombination. Single-nucleotide polymorphisms are shown to be related with cancer incidence. The aim of the present study was to examine the association between the L757P polymorphism at exon 13 of the EXO1 gene and the risk of CRC in Iranian patients.
  
  
  METHODS
  In this case-control study, 90 cases and 98 healthy control samples were analyzed genetically. The EXO1 polymorphism, P757L, was analyzed by polymerase chain reaction-restriction fragment length polymorphism. The obtained polymorphisms were examined for the relationship with CRC risk and also clinicopathological characteristics.
  
  
  RESULTS
  Our findings showed that patients with the Leu/Leu genotype have a reduced risk of CRC (adjusted odds ratio [OR] = 0.192, 95% confidence interval [CI]: 0.040-0.921) when the Pro/Leu and Pro/Pro genotypes were blended and they were considered as the reference. The Leu/Leu genotype also showed a reduced risk (adjusted OR = 0.168, 95% CI: 0.034-0.816) when the Pro/Pro genotype was a reference; nevertheless, the Pro/Leu genotype did not reveal a significant association with CRC at the same status (adjusted OR = 0.686, 95% CI: 0.367-1.284).
  
  
  CONCLUSIONS
  Our results provide evidence diagnosing that the Leu/Leu genotype of EXO1 showed an inverse association with CRC. In addition, despite other investigations, we could define a significant association between the Leu allele and CRC (p = 0.001).
authors.affiliation: Research Center for Gastroenterology and Liver Diseases, Taleghani Hospital, Shaheed Beheshti Medical University, Tehran, Iran. mah_haghighi@hotmail.com
authors.forename: Mahdi Montazer
authors.initials: MM
authors.lastname: Haghighi
authors.forename: Mohammad Yaghoob
authors.initials: MY
authors.lastname: Taleghani
authors.forename: Seyed Reza
authors.initials: SR
authors.lastname: Mohebbi
authors.forename: Mohsen
authors.initials: M
authors.lastname: Vahedi
authors.forename: Seyed Reza
authors.initials: SR
authors.lastname: Fatemi
authors.forename: Narges
authors.initials: N
authors.lastname: Zali
authors.forename: Atena Irani
authors.initials: AI
authors.lastname: Shemirani
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zali
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000235:genetics*; D000368:Aged; D019943:Amino Acid Substitution; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D005090:Exodeoxyribonucleases / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
chemical_list: C114331:EXO1 protein, human; D005090:Exodeoxyribonucleases; D045643:DNA Repair Enzymes