Analysis of genetic alterations associated with hereditary non-polyposis colorectal cancer.

We have gained further progress in molecular diagnosis in Slovakia and in research of basic mechanisms of hereditary predisposition particularly to cancers of gastrointestinal tract. In addition to the identification of new germline mutations in the MLH1 and MSH2 genes, we have revealed first inherited changes of MSH6 and LKB1/STK11 genes in Slovak population by sequencing analysis. We have established a multiplex ligation-dependent probe amplification of MLH1 and MSH2 genes by which we were able to identify first multi-exon alterations in the HNPCC patients in which the changes of the gene were not detectable by DNA sequencing before. The finding of mutations in patients as well as asymptomatic relatives is important for early diagnosis and treatment of neoplasia. We have also developed an original pre-screening system for prediction of mutated gene in HNPCC based on detection of heterozygosity of relevant allele in tumor by using SNP markers and multiplex SNaPshot. The system is applicable in clinics.