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

Genomic instability is sometimes due to impairment of DNA repair systems, w hich results in a change in the number of microsatellite repeats in tumor c ells, produced by slippage during DNA replication. Such abnormal repeats ar e manifested as microsatellite instability (MSI). We have devised a simple assay using four-color fluorescence for the detection of MSI by an automati c sequencer. Using this method, MSI and loss of heterozygosity (LOH) at fou r microsatellite loci can be identified simultaneously. We have also develo ped an algorithm and software for automated analysis of MSI and LOH with th is 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 pa tients with hereditary nonpolyposis colorectal cancer (HNPCC), meeting the Amsterdam Minimum Criteria, were found to exhibit MSI. (C) 1999 Elsevier Sc ience B.V. All rights reserved.