Extended Data Fig. 1: Summary mutation metrics for C3H and CAST tumours.

a, Single nucleotide substitution rates per C3H tumour, rank ordered over x-axis (grey points, median blue line). Insertion/deletion (indel, <11 nt) rates show as black. b, Y-axis from a, expanded to show distribution of indel rates with preserved tumour order. c, Number of C3H copy number variant (CNV) segments and their total span as a percent of the haploid genome. Blue shading shows intensity of overlapping points as a percent of all tumours in the plot. d–f, Corresponding plots for CAST derived tumours; f, two extreme x-axis outliers relocated (red) and x-axis value shown. g, h, Mutation spectra deconvolved from the aggregate spectra of 371 C3H tumours, subsequently referred to as the DEN1 and DEN2 signatures. DEN1 is dominated by T→N or their complement A→N changes thought to arise from the O⁴-ethyl-deoxythymidine adduct of T¹⁰. DEN2 substitutions are primarily C→T or their complement G→A changes likely from O⁶-ethyl-2-deoxyguanosine lesions of G¹⁰. i, Oncoplot summarizing mutation load, mutation signature composition, and driver gene mutation complement of C3H tumours. j, Oncoplot of CAST derived tumours as in i. The DEN2 signature is a minor component of most tumours but prominent in a minority (i, j).