Analysis of R213R and 13494 g-->a polymorphisms of the p53 gene in individuals with esophagitis, intestinal metaplasia of the cardia and Barrett's Esophagus compared with a control group

Abstract

Protein p53 is the tumor suppressor involved in cell cycle control and apoptosis. There are several polymorphisms reported for p53 which can affect important regions involved in protein tumor suppressor activity. Amongst the polymorphisms described, R213R and 13949 g-->a are rarely studied, with an estimate frequency not yet available for the Brazilian population. The purpose of this study was to investigate the genotype and allele frequencies and associations of these polymorphisms in a group of patients with altered esophageal tissue from South Brazil and compare with the frequency observed for a control population. A total of 35 patients for R213R and 45 for 13494 g-->a polymorphisms analysis with gastroesophageal reflux disease (GERD) symptoms diagnosed by upper digestive endoscopy and confirmed by biopsy were studied. For both groups, 100 controls were used for comparison. Loss of heterozygosity (LOH) was also analyzed for a selected group of patients where normal and affected tissue was available. There was one patient with Barrett's Esophagus (BE) showing LOH for R213R out of two heterozygous samples analyzed and two patients (esophagitis and BE) for 13494 g-->a polymorphism. We also aimed to build a haplotype for both polymorphisms collectively analyzed with R27P polymorphism, previously reported by our group. There were no significant differences in allele and genotype distribution between patients and controls. Although using esophagitis, intestinal metaplasia of the cardia and BE samples, all non-neoplastic lesions, we can conclude that these sites do not represent genetic susceptibility markers for the development and early progression of GERD to BE and esophageal cancer. Additional studies are required in order to investigate other determiners of early premalignant lesions known to predispose to esophageal cancer.

Fig. 1

Agarose gel (3.0%) showing long PCR results and digestions carried out with TaqI and MspI. Position 8 shows the 100 bp molecular weight marker. Position 1 shows the long PCR product concerning exons 5 to 8 in the TP53. Positions 2, 3 and 4 show the allelic patterns AA and AG for the R213R polymorphism. Positions 5, 6 and 7 show the allelic patterns AA, AG and GG for the 13494 g→a polymorphism