title: Association of microsomal epoxide hydrolase exon 3 Tyr113His and exon 4 His139Arg polymorphisms with gastric cancer in India.
abstract: BACKGROUND
  Microsomal epoxide hydrolase, an important phase II xenobiotic enzyme, exhibits polymorphisms at exon 3 (Tyr113His [T/C]) and exon 4 (His139Arg [A/G]), which modulate enzyme activity; this may affect susceptibility to cancers. We studied association between these polymorphisms and gastric cancer (GC).
  
  
  METHODS
  In a prospective study, 77 patients with GC, 50 with peptic ulcer, and 160 healthy controls (HC) were genotyped for exon 3 (PCR-RFLP followed by sequencing) and exon 4 (PCR-RFLP). Helicobacter pylori was considered to be present if two of three tests (histology, rapid urease test, and IgG antibody) were positive.
  
  
  RESULTS
  Tyr113His and His139Arg genotypes and haplotypes were comparable among groups. 113His carriers were commoner among H. pylori-negative patients with GC than HC (p-value = 0.019, odds ratio (OR) = 2.5, 95 % confidence interval (CI) = 1.2-5.4). Haplotype combination of exons 3 and 4 113Tyr-139Arg (TA) were associated with higher and reduced risk in patients with GC than HC in presence and absence of H. pylori (25 % vs. 11 %; p-value = 0.033, OR = 2.61, 95 % CI = 1.08-6.3 and 11.6 % vs. 28.7 %; p-value = 0.004, OR = 0.33, 95 % CI = 0.15-0.7, respectively).
  
  
  CONCLUSIONS
  Though 113Tyr-139Arg was associated with GC in presence of H. pylori, in its absence, it appeared to be protective. Exon 3, 113His, however, was associated with GC even in absence of H. pylori infection.
authors.affiliation: Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226 014, India. ujjalaghoshal@yahoo.co.in
authors.forename: Ujjala
authors.initials: U
authors.lastname: Ghoshal
authors.forename: Sushil
authors.initials: S
authors.lastname: Kumar
authors.forename: Virendra
authors.initials: V
authors.lastname: Jaiswal
authors.forename: Shweta
authors.initials: S
authors.lastname: Tripathi
authors.forename: Balraj
authors.initials: B
authors.lastname: Mittal
authors.forename: Uday C
authors.initials: UC
authors.lastname: Ghoshal
mesh_terms: D004273:DNA, Neoplasm / Q000235:genetics*; D004851:Epoxide Hydrolases / Q000235:genetics* / Q000378:metabolism; D005091:Exons; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D013274:Stomach Neoplasms / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm; D004851:Epoxide Hydrolases; C522330:EPHX1 protein, human