title: Correlation between global genome methylation and mutation at CpG codons of p53 gene.
abstract: OBJECTIVE
  Hypomethylation within the body of the p53 gene, which is normally methylated, has been found in neoplasms. Also, the CG → TA transition was not detected in the CpG codons of the p53 gene in gastritis lesions in Iranian patients. Therefore, an evaluation of the probable correlation between global genome methylation and alteration at CpG codons of p53 gene was needed.
  
  
  METHODS
  For defining the genotypes of CpG codons, DNA sequencing was performed on 90 paired samples of gastritis and normal tissues. To measure global genome methylation status, the extracted DNA was digested with HpaII (methylation sensitive) and MspI (insensitive). Then, enzymatic digestion was quantitated using Pyrosequencing as peak height. By calculating the HpaII/ MspI peak ratio it is possible to evaluate the methylation level of normal and gastritis tissues.
  
  
  RESULTS
  Codons 9, 245 and 248 underwent a CG → AT transversion but not a CG → TA transition. In addition, the mean methylation level was significantly different between the patients with GG and GT genotypes at codon 245 (P = 0.019).
  
  
  CONCLUSIONS
  As CG → AT transversion at codon 245 is associated with global genome methylation, GG hypomethylation may induce different pattern of mutations, for example, C → A instead of C → T at the CpG codons of the p53 gene during gastritis development in Iranian patients.
authors: Gastroenterology and Liver Diseases Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. najjarsadeghi@yahoo.com
authors: Rouhallah
authors: R
authors: Najjar Sadeghi
authors: Mohsen
authors: M
authors: Vahedi
authors: Homayon
authors: H
authors: Zojaji
authors: Mohamad Reza
authors: MR
authors: Zali
mesh_terms: D000328:Adult; D003062:Codon; D018899:CpG Islands; D019175:DNA Methylation; D005260:Female; D005756:Gastritis / Q000235:genetics*; D016158:Genes, p53; D015894:Genome, Human; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation
chemical_list: D003062:Codon