The MSI analysis performed on the patients with Hereditary Nonpolyposis Colorectal Cancer is available in our Center.

Hereditary Nonpolyposis Colorectal Cancer (HNPCC) is an autosomal predisposition syndrome and constitutes 4-6% of the colorectal cancers. It is caused by the mutations in DNA repair genes such as MLH1, MSH2, MSH6 and PMS2 (MMR – mismatch repair). The mutations in MMR genes are characterized with the impairment in the repair mechanism during DNA replication. The disease shows itself with colorectal adenocarcinoma (Lynch Type I) or, in addition to this, with cancers such as endometrial, over, gastric, urethra, renal pelvis, and small bone etc. (Lynch Tip II).

Microsatellite Instability (MSI) is the observation of extra microsatellite alleles in the tumor DNA depending to the inactivation in MMR genes. In cases where it is suspected from HNNPC and where the hereditary mutation is not known, searching for MSU in tumor cells is the diagnosis to be made at first stage. While MSI is observed in most of the patients with HNNPC, this rate is around 15-20% in sporadic colorectal cancers. This test is not used in HNNPC diagnosis, while it reveals the requirement to examine the MMR genes in facts with determined MSI.