To determine whether enrichment of MLH1 mutation is reduced in BRCA2 mutant samples in comparison with non-MLH1 MMR genes, we pooled multiple TCGA data sets and examined MLH1 mutation versus PMS2/MSH6/MSH2 in MSI-high (microsatellite instability) cancer samples (n = 10,068). This evidence concerns the gene MRC1 and cancer.