Fig. 2.

Base substitution mutational signatures in primary colorectal cancers. a Relative contribution of the various base substitution mutational signatures (as designated in COSMIC and described by Alexandrov et al.) in the two samples with HRD scores ≥ 42 and available whole-exome sequencing data. b Relative contribution of mutational signatures in the three samples where signature 3 was most dominant. One sample harboured a frameshift mutation in POLQ and a missense mutation in XAB2 with mutant allele fractions of 0.30 and 0.66, respectively. Another sample had a missense mutation in C19orf40 with a mutant allele fraction of 0.21, while no mutations in homologous recombination-related genes were detected in the last sample. None of these three tumours had DNA copy number data and HRD scores available. The frequency of different types of base substitutions for Fig. 3a and b is shown in Supplementary Fig. S2a–b. c Comparison of HRD scores in MSS tumours according to relative contribution of signature 3. P value from independent samples t-test.