Molecular screening of potential HNPCC patients using a multiplex microsatellite PCR system

Microsatellite instability (MSI) is a molecular hallmark of the Hereditary Non-Polyposis Colorectal Cancer (HNPCC) syndrome occurring in about 80-90% of the tumours and also in sporadic tumours of different organs, albeit at lower frequency. Highly unstable colorectal tumours (MSI-H) have different histopathological features and tend to have better prognosis compared to ne oplasms without (MSS) or with low levels of microsatellite instability (MSI -L). Since MSI classification allows the identification of potential HNPCC patients and might represent a valuable diagnostic parameter an increasing demand for high-throughput microsatellite analysis will arise. Therefore, w e have adapted five diagnostic microsatellites, m(odified) ACTC, mBAT26, mD 5S107, mD5S406 and mD13S153, to allow coamplification. Using this multiplex polymerase chain reaction (PCR) system 29 colorectal tumour tissues with k nown MSI status could be unambiguously identified as MSI-H (13 cases) or MS I-L/MSS (16 cases). Highly unstable colorectal tumour detection frequency o f individual markers reached 77% (mD5S406), 85% (mACTC), 85% (mD5S107), 92% (D13S153) and 100% (mBAT26) showing similar sensitivity but improved speci ficity as compared with a microsatellite reference panel. In a prospective analysis of 31 colorectal tumours, the multiplex PCR system identified five MSI-H cases. Multiplex MSI PCR is a time saving and cost-effective method not restricted to specific technical equipment and applicable to a variety of microsatellite-based genotyping approaches. (C) 1999 Academic Press.