MSI (Microsatellite Instability)
MSI is the detection and determination of MicroSatellite Instability (MSI) levels, which characterizes different subtypes of tumors in many cancers and is caused either by mutations or by epigenetic inactivation (hypermethylation of the promoter of the M gene the correction of "mismatches" (MisMatch Repair genes - MMR). It is detected in ~ 15% of cases of stage II and III colon cancer (CRC).
Method: In DNA from whole blood and FFPE sections the polymorphic regions BAT25, BAT26, NR21, NR24, MONO27 are tested. These are characterized as almost monomorphic which makes them ideal markers for MSI as well as the polymorphic regions PentaD and PentaC for confirmation of origin of the two materials from the same incident using the MSI v1.2®Promega kit followed by capillary electrophoresis in a genetic analyzer ABI3130xl (ThermoScientific).