<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>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 microsatellite instability may be a defect in the ability to repair mistakes made when DNA is copied in the cell.</n0:def-definition><n0:def-source>NCI-GLOSS</n0:def-source></n0:ComplexDefinition>
<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Genomic instability associated with defective DNA mismatch repair in tumors.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>
nci:P98
Microsatellites are stretches of DNA in which a short motif (usually one to five nucleotides long) is repeated several times. Instability of these regions is initiated when mutations in genes that repair damaged DNA cause these regions to get longer or shorter. Hereditary colon cancer syndrome is associated with mutations in the DNA mismatch repair genes, which may result in alterations in the nucleotide sequence.