What is MSH2 gene?

What is MSH2 gene?

The MSH2 gene provides instructions for making a protein that plays an essential role in repairing DNA. This protein helps fix errors that are made when DNA is copied (DNA replication) in preparation for cell division.

What does microsatellite stable mean?

The DNA is considered stable when the number of microsatellite repeats is the same in all the cells of the body, also referred to as microsatellite stable or MSS. DNA mismatch repair (MMR) is a quality control and “spell checking” process that is responsible for making sure the DNA is copied without errors.

What is MSI testing?

Microsatellites are regions of repeated DNA that change in length (show instability) when mismatch repair is not working properly. MSI testing looks at the length of certain DNA microsatellites from the tumor sample to see if they have gotten longer or shorter as a measure of instability.

What causes mismatch repair?

1 Mismatch Repair. MMR mainly repairs DNA lesions caused by faulty DNA replication or repair, resulting in mismatches or small insertion and deletion loops, or deamination of 5-methylcytosine. Failure of MMR is often associated with point mutations or microsatellite instability (Fig. 29.1).

Where is MSH2 gene found?

chromosome 2
DNA mismatch repair protein Msh2 also known as MutS homolog 2 or MSH2 is a protein that in humans is encoded by the MSH2 gene, which is located on chromosome 2.

Is microsatellite stability good or bad?

Microsatellite instability (MSI) is caused by mutations in DNA mismatch repair genes such as MLH1, MSH2, MSH6, and PMS2, and it is found in 10% to 15% of sporadic colorectal cancers (CRCs). The presence of MSI predicts a good outcome in colorectal cancer.

Why are microsatellites useful?

Microsatellites provide data suitable for phylogeographic studies that seek to explain the concordant biogeographic and genetic histories of the floras and faunas of large-scale regions. They are also useful for fine-scale phylogenies — up to the level of closely related species.

How is MSI detected?

To detect MSI, fluorescently labeled primers are used to amplify fragments from the tumor and matched normal samples. The amplified fragments are separated by size using capillary electrophoresis, and the fluorescent labelling allows them to be separated by the color of the fluorescent tag.

When does mismatch repair happen?

Mismatch repair happens right after new DNA has been made, and its job is to remove and replace mis-paired bases (ones that were not fixed during proofreading). Mismatch repair can also detect and correct small insertions and deletions that happen when the polymerases “slips,” losing its footing on the template 2.

What are the steps in mismatch repair?

Mismatch repair

1. A mismatch is detected in newly synthesized DNA.
2. The new DNA strand is cut, and a patch of DNA containing the mispaired nucleotide and its neighbors is removed.
3. The missing patch is replaced with correct nucleotides by a DNA polymerase.
4. A DNA ligase seals the remaining gap in the DNA backbone.

What causes MSH2 mutation?

Your close relatives (like your parents, brothers, sisters, children) have a 50/50 random chance of inheriting the MSH2 mutation that you carry, and other family members (like your aunts, uncles, cousins) may also inherit it. Your relatives can be tested for this same mutation.

Can you survive Lynch syndrome?

Currently, there is no cure for Lynch syndrome. Patients with Lynch syndrome should undergo lifelong cancer screening beginning in adulthood.

What type of mutation is MSH2?

Inherited mutations in the MSH2 gene are associated with Lynch syndrome . Other names for Lynch syndrome include Hereditary Nonpolyposis Colorectal Cancer ( HNPCC ) and Muir-Torre syndrome, which refers to a subset of Lynch syndrome in which people have an increased risk of developing uncommon skin tumors.

How do you test for microsatellite instability?

There are several methods that can be used to detect microsatellite instability (MSI) or deficient DNA mismatch repair (dMMR). The two most common methods are polymerase chain reaction (PCR) and immunohistochemistry (IHC). MSI testing by PCR is the accepted gold standard method for MSI detection(1).

What does high microsatellite instability mean?

Microsatellite instability-high cancer cells may have a defect in the ability to correct mistakes that occur when DNA is copied in the cell. Microsatellite instability is found most often in colorectal cancer, gastric cancer, and endometrial cancer, but it may also be found in many other types of cancer.