A change that occurs in the DNA of certain cells (such as tumor cells) in which the number of repeats of microsatellites (short, repeated sequences of DNA) is different than the number of repeats that was in the DNA when it was inherited. The cause of MSI may be a defect in the ability to repair mistakes made when DNA is copied in the cell. Also called microsatellite instability.

A characteristic of cells that contain an abnormality in DNA mismatch repair (see microsatellite). For example, the presence of MSI in colorectal tumor tissue may be used as a marker for germline mutations in one of the DNA mismatch repair genes associated with HNPCC. MSI can also occur sporadically, and in these cases is related to gene hypermethylation. This is an issue in the differential diagnosis of HNPCC. Also called microsatellite instability.

Cambio que se presenta en el ADN de ciertas células (como las células tumorales) por el que el número de repeticiones de los microsatélites (secuencias cortas y repetidas de ADN) es diferente al número de repeticiones que tenía el ADN cuando se heredó. La causa de la IMS puede ser un defecto en la capacidad de reparar errores cuando el ADN se copia en la célula. También se llama inestabilidad microsatélite.