How do you interpret discrepancies between MMR testing and MSI testing?

Microsatellites are short repetitive sequences of 1 to 6 base pairs of DNA throughout the genome, mostly in noncoding regions. MSI tumors develop through a distinctive molecular pathway characterized by genetic instability in microsatellite DNA repeat sequences. MSI phenotype occurs due to germline mutations in mutL homologue 1(MLH1), mutS homologue 2 (MSH2), mutS homologue 6 (MSH6), or postmeiotic segregation increased 2 (PMS2). MSI/dMMR is a predictive biomarker for immunotherapy and can be te...