MRC1 and neoplasm: Ten of the 127 evaluable tumors (8%) showed loss of either one or two MMR proteins in tumor tissue defining MMRD and potentially indicating underlying germline MMR gene alterations (referred to as germline MMRD) (6/10; 60% loss of MSH2 and MSH6, 3/10; 30% loss of MLH1 and PMS2, 1/10; 10% loss of MSH6) (Fig. 1c; interpretation of IHC results in Fig. S2).