USE OF SSCP ANALYSIS TO IDENTIFY GERMLINE MUTATIONS IN HNPCC FAMILIESFULFILLING THE AMSTERDAM CRITERIA

Hereditary non-polyposis colorectal cancer (HNPCC) is a clinical syndr ome characterised by an inherited predisposition to early onset colore ctal and uterine cancers and an increased incidence of other cancers. It is caused by germline defects in the human mismatch repair genes. D efects in two of the known mismatch repair genes (namely hMSH2 and hML H1) account for over 90% of mutations found in HNPCC families. In this study we have identified 14 families that fulfilled the clinical crit eria for HNPCC and screened the hMSH2 and hMLH1 genes for germline mut ations using single-strand conformational polymorphism (SSCP) analysis and DNA sequencing. Seven mutations were identified. Of these, there were five frameshifts, one missense mutation and a further novel mutat ion that involved separate transition and transversion changes in succ essive amino acid residues. Three of the mutations were in hMSH2 and f our in hMLH1. The identification of germ-line mutations in an HNPCC fa mily enables targeted surveillance and the possibility of early curati ve intervention. SSCP is a simple and effective method for identifying most mutations in the human mismatch repair genes using DNA from fres h, frozen or archival material.