Maximum parsimony phylogenetic trees were reconstructed using SNV mutation data with cases UCL_1018 displayed. Branch length is proportional to the number of mutations. Inset shows clinicopathological characteristics. Branches are colored according to MSH6 IHC labeling, with blue indicating MSH6-proficient and pink indicating MSH6-deficient lineages. High-power photomicrographs show MSH6, MSH3 and MSH2 labeling as indicated. Dashed lines indicate the border between proficient and deficient labeling; asterisk indicates the absence of labeling throughout; arrowheads indicate small reverter clones throughout. Trees are labeled with pertinent immune escape mutations. MS length distribution shows MSIsensor output where peak height is proportional to allelic frequency, with beige indicating reference C8 or A8 length, dark gray indicating expanded or contracted alleles and red indicating +3 frameshift. Phylogenetic trees were generated for all n = 10 tumors (Extended Data Fig. 10 ). Yo, year old.
