Microsatellite Instability In Inflammatory Bowel Disease.

Long-standing Inflammatory Bowel Disease (18D) is a condition at increased colon cancer risk.Mutation or "instability" of microsatellite DNA sequences (MSI) are markers for mutation of genes which are involved in the DNA mismatch repair (MMR)system.MSI has previously reported in non cancerous mucosa of patients with Ulcerative Colitis (UC) and it has been speculated that this finding may be due to an oversaturation of MMR system associated to an increase of epithelial cell proliferation, caused by chronic inflammation.METHODS: In this study we analized five microsatellite markers (02S123, BAT-26, BAT-25, IGFIIR, TGFf3IIR) in biopsy samples taken from 20 patients with UC and 4 patients with Crohn's Disease (CD).Clinical activity, endoscopic and histological scores, degree of inflammationand the presence or absence of high-grade dysplasia were recorded for each patient.RESULTS: Frameshift mutation in the poly-(A)IO tract of BAT-26 was found in only one case of CD.Tissue in which MSI was observed had been taken from the right-colon; no dysplasia was found and only a moderate inflammation was present in the sample.No MSI was detected in other colonic areas of the same patient.CONCLU-SIONS: In contrast with previous reports, MSI was very rare in this series of patients with IBD.However the detection of MSI in non dysplastic mucosa and in absence of intense inflammation , raises the question whether MSI can be used as an early predictor marker for colon cancer risk.