Clinical Significance
MSI is a key factor in several cancers including colorectal, endometrial, ovarian and gastric cancers. Colorectal cancer studies have demonstrated two mechanisms for MSI occurrence.
- The first is in hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch Syndrome, where an inherited mutation in a mismatch-repair gene causes a microsatellite repeat replication error to go unfixed. Most cases result in changes in the lengths of dinucleotide repeats of the nucleobases cytosine and adenine (sequence: CACACACACA...). The change in nucleotide repeats is an indicator of a faulty DNA repair system, which can ultimately lead to cancer.
- The second mechanism whereby MSI is a marker for colorectal cancer is an epigenetic change that silences an essential mismatch-repair gene.
In both cases, microsatellite insertions and deletions indicate inappropriate DNA repair, resulting in uncontrolled cell division and tumor growth.
Read more about this topic: Microsatellite Instability
Famous quotes containing the word significance:
“It is necessary not to be Christian to appreciate the beauty and significance of the life of Christ.”
—Henry David Thoreau (1817–1862)