Mismatch Repair Gene (MMR)

What is the Mismatch Repair (MMR) Gene IHC Test?

This test analyzes tissue samples to detect the expression of mismatch repair (MMR) proteins using immunohistochemistry (IHC). MMR proteins repair DNA errors during cell division, and their loss indicates microsatellite instability (MSI), commonly associated with Lynch syndrome and colorectal cancer.


Who should get this test?

This test is recommended for:

Patients diagnosed with colorectal or endometrial cancer.
Individuals with a family history of Lynch syndrome.
Those with suspected hereditary cancer syndromes.



How is the test performed?

A tissue biopsy is collected, and the sample is stained using IHC to evaluate the expression of MMR proteins (MLH1, MSH2, MSH6, and PMS2).


What do the results indicate?


Normal Expression: Intact MMR protein expression suggests proficient DNA repair.
Loss of Expression: Indicates MMR deficiency and possible microsatellite instability.



Why is this test important?

MMR testing helps guide treatment decisions, identify Lynch syndrome, and determine eligibility for immunotherapy.