Familial adenomatous polyposis: analysis of genetic instability of microsatellites Loci and genetic alternations of tumor suppressor genes.

Familial adenomatous polyposis (FAP) is an autosomal dominant illness with the highest risk for appearance of colorectal cancer's disease. In our study, we have used Bethesda criteria that define colorectal cancers which can be tested on microsatellite instability. The aim of our study is make an analysis of microsatellite instability (MSI), appearance of RER+ phenotype, genetic alteration of tumor suppressor genes as like as one of responsible factor for genesis of adenomatous polyposis. The base for this study were shown families with clinical diagnosed FAP. In this study two families with clinical diagnosed adenomatous polyposis were involved. Our study of both families showed that three tumor tissues belonged to RER negative phenotype, but only one belonged to RER positive phenotype. Microsatellite analysis showed instability of mononucleotide marker Bat 40 at 4 samples and Bat 26 at 2 samples, but Bat 25 and in 1 sample. Dinucleotide marker TP 53 did no show any microsatellite alterations. Genetic alteration of tumor suppressor gene APC appeared at 4 samples, p53 at 3 samples, RB1 at 2 samples and NM23 only at 1 sample, but tumor suppressor genes DCC1 and DCC2 were homozygote. Our results are agree with results of earlier studies and also the got results confirm the fact that loss of heterozygosity of tumor suppressor gene APC and p53 are responsible for genesis of adenomatous polypose and it also represents the characteristic of genetic changes FAP's patients in our region.