Mutational Signatures (v3 - May 2019)
Single Base Substitution (SBS) Signatures
Many of the SBS vignettes have four figures. Within each vignette:
The first figure (eg SBS1 in the first vignette) shows the signature profile using the conventional 96 mutation type classification. This classification is based the six substitution subtypes: C>A, C>G, C>T, T>A, T>C, and T>G (all substitutions are referred to by the pyrimidine of the mutated Watson—Crick base pair). Further, each of the substitutions is examined by incorporating information on the bases immediately 5’ and 3’ to each mutated base generating 96 possible mutation types (6 types of substitution x 4 types of 5’ base x 4 types of 3’ base). Mutational signatures are displayed and reported based on the observed trinucleotide frequency of the human genome, i.e., representing the relative proportions of mutations generated by each signature based on the actual trinucleotide frequencies of the reference human genome version GRCh37.
The second figure (eg SBS1-TSB in the first vignette) shows the signature profile on transcribed and untranscribed strands of genes using the 192 mutation type classification.
The third figure, "Cancer types in which the signature is found," shows the numbers of mutations per megabase attributed to each mutational signature in samples with the signature. Only those cancer types with tumors in which signature activity is attributed are shown. The numbers below the dots for each cancer type indicate the number of tumors in which the signatures was attributed (above the blue horizontal bar) and the total number of tumors analyzed (below the blue bar).
The fourth figure, "Differences between current and previous profiles," is only shown for signatures for which there has been a similar figure previously shown in COSMIC.
The signatures are available in numerical form from synapse.org ID syn12009743.