MICROSATELLITE INSTABILITY AND LOSS OF HETEROZYGOSITY IN MAMMARY-CARCINOMA AND ITS PROBABLE PRECURSORS

Microsatellite instability is a farm of genetic damage that may be due to defective mismatch repair genes and may be a marker of processes l eading to malignancy. We have analysed a series of epithelial hyperpla sia of usual type, carcinomas in situ and invasive and metastatic carc inomas from the mammary gland on the assumption that they represent st ages in the evolution of mammary carcinoma. Eight markers on chromosom es 3p, 4q, 9p, 11p, 14q, 17p, 17q and Xq were examined for microsatell ite instability and loss of heterozygosity. High rates of loss on chro mosomes 17p, 17q and Xq indicate that these chromosomal arms contain g enes important in mammary carcinogenesis. The rate of microsatellite i nstability observed in this study was uniformly low, irrespective of t he lesion. This implies that microsatellite instability is not a marke r of malignancy in most instances of mammary neoplasia.