Abstract for presentation at 11th International Congress of Human Genetics

Gastroesophageal Reflux Disease (GERD), if not treated, can lead to Barrett’s esophagus and cancer. This study aimed to give some contribution for the early diagnosis, prognosis and identification of individuals likely to develop esophageal cancer. With the use of Comet assay methodology, alkaline version (pH 13), we have studied DNA breakages in esophageal mucosa cells and peripheral blood lymphocytes of 30 voluntary GERD patients: 10 of them had normal esophageal mucosa and were used as controls; 8 had mild esophagitis (grades I and II); 5 had severe esophagitis [grades III and IV (Barrett)]; and 7 had esophageal cancer. All of them were not tobacco, alcohol or drug users. In blind test, 5,000 cells (50 per slide, amounting to 200 cells per individual) were analyzed after staining with ethidium bromide under fluorescence microscope Axiophot II, Zeiss. The quantification of DNA damages was done by visual scoring (1 to 4) (Collins, 2004) and by Interactive Image Analysis System Comet Assay II of Perceptive Instruments. The main parameter measured in the system was the tail moment (length of the tail X intensity of the tail, or frequency of migrated DNA). Data analysis about Tail Moment and Scoring parameters showed a high frequency of breakages among GERD carrier individuals with severe esophagitis and cancer, when compared to controls. A large number of Class 4 Comet cells was found in the esophageal mucosa biopsies and, in a smaller number, in peripheral blood cells from severe esophagitis and cancer patients. We suggest that increased DNA breakage frequency is directly related to the mucosa inflammation degree. We also assume that Comet assay appears to be a promising technique for early diagnosis of esophageal cancer, as well as a prognosis test. FAPESP, CNPq.