What is the MMR System?
The
MMR system, or
Mismatch Repair system, is a critical cellular mechanism responsible for correcting errors that occur during DNA replication. These errors include mismatches of bases and insertion-deletion loops. The MMR system is essential for maintaining
genomic stability and preventing mutations that can lead to cancer.
How Does the MMR System Work?
The MMR system detects and repairs mismatched DNA base pairs and small insertion-deletion loops that escape the proofreading activity of DNA polymerases. Key proteins involved in this process include
MutS and
MutL homologs. Once a mismatch is detected, these proteins initiate a series of steps to remove the incorrect DNA segment and fill in the correct sequence.
What is Lynch Syndrome?
Lynch Syndrome is an inherited disorder caused by germline mutations in MMR genes such as
MLH1,
MSH2,
MSH6, and
PMS2. Individuals with Lynch Syndrome have a significantly increased risk of developing colorectal cancer and other cancers, including endometrial, ovarian, and gastric cancers.
What is the Prognosis for Patients with MMR Deficiency?
The prognosis for patients with MMR deficiency varies depending on several factors, including the type of cancer and the stage at diagnosis. Generally, tumors with high microsatellite instability may have a better prognosis due to their increased immunogenicity and responsiveness to immunotherapy. However, early detection and appropriate management are crucial for improving outcomes.
Conclusion
The MMR system plays a vital role in maintaining genomic integrity and preventing cancer. Understanding the mechanisms of MMR, the implications of its deficiency, and the available diagnostic and therapeutic options is essential for managing cancers associated with MMR defects.
