Lacking mismatch repair (dMMR) is a genetic alteration wherein the DNA repair system cannot repair replication errors. This leads to microsatellite instability (MSI), a useful cancer biomarker.
🔬 Why it matters:
dMMR/MSI tumors have a high mutation burden.
They respond beautifully to immunotherapy (like PD-1 checkpoint inhibitors).
Global MSI/dMMR testing for newly diagnosed cancers is recommended by international guidelines.
How it is diagnosed today:
Immunohistochemistry (IHC): detects loss of MMR proteins (MLH1, MSH2, MSH6, PMS2). Rapid and cost-effective, with low sensitivity.
PCR (MSI-PCR): 2006 gold standard, but only usually for colorectal/gastric tumors, and tissue biopsy + normal DNA required.
Next-Generation Sequencing (NGS): detects MSI directly from tumor or even blood (liquid biopsy), scalable across all cancer types.
At MSInsight, our MSIcare product employs NGS to detect MSI/dMMR with near-perfect sensitivity, without the need for matched normal DNA. One sample is sufficient — which speeds the test, simplifies it, and makes it more economical.
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