Microsatellites are repetitive sequences. Microsatellite Instability (MSI) relates to the misfunction of the DNA Mismatch Repair (MMR) gene that can introduce errors, in length or sequence, that result in novel repetitive sequences. MSI is most closely associated with colon cancers but shows prevalence in multiple other cancer types.
MSI is used in cancer diagnostics to aid the determination of an appropriate course of treatment for a patient. qPCR and NGS workflows are used to determine MSI status in patient samples. This standard has been shown to work with the Promega MSI kit, the Titano MSI kit, the Biocartis Idylla MSI kit and a laboratory developed test which utilises the Illumina MiSeq Sequencer.