There were 12 tumors that were classified as dMMR by MMR IHC but determined to be pMMR by the additive feature combination approach giving an overall accuracy between tumor panel sequencing derived dMMR status and the MMR IHC status of 92% (95% confidence intervals, CI 86.5–92%) (Additional file 1: Table S3). The gene discussed is MRC1; the disease is neoplasm.