MRC1 and Lynch syndrome: To assess whether tumor features and somatic profiles generated using tumor panel sequencing could inform MMR VUS classification, tumor features associated with Lynch syndrome were assessed on 28 tumors collected from the 25 VUS carriers in this study (Table 1), and compared with a reference group of dMMR tumors from known germline MMR pathogenic variant carriers (n = 16) and pMMR tumors from non-MMR carriers (n = 18) that previously underwent tumor panel sequencing (Table S1).