Automated and simultaneous identification of microsatellite instability by fluorescence-based polymerase chain reaction (PCR) in four loci

Genomic instability is sometimes due to impairment of DNA repair systems, which results in a change in the number of microsatellite repeats in tumor cells, produced by slippage during DNA replication. Such abnormal repeats are manifested as microsatellite instability (MSI). We have devised a simple assay using four-color fluorescence for the detection of MSI by an automatic sequencer. Using this method, MSI and loss of heterozygosity (LOH) at four microsatellite loci can be identified simultaneously. We have also developed an algorithm and software for automated analysis of MSI and LOH with this method. Using our method for the detection of MSI in four microsatellite loci and the algorithm and software that we developed, 18 (94.7%) of 19 patients with hereditary nonpolyposis colorectal cancer (HNPCC), meeting the Amsterdam Minimum Criteria, were found to exhibit MSI. (C) 1999 Elsevier Science B.V. All rights reserved.