Mutational Signatures (v3.2 - March 2021)
SBS93 · GRCh37 · COSMIC v93
Mutational profile using the conventional 96 mutation type classification. This classification is based on the six substitution subtypes: C>A, C>G, C>T, T>A, T>C, and T>G, as well as the nucleotides immediately 5’ and 3’ to the mutation.
Each of the substitutions is referred to by the pyrimidine of the mutated Watson—Crick base pair. Incorporating information on the bases immediately 5’ and 3’ to each mutated base generates 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 genome, i.e., representing the relative proportions of mutations generated by each signature based on the actual trinucleotide frequencies of the corresponding reference genome.
Summary of the technical and experimental evidence available in the scientific literature regarding the validation of the mutational signature.
|Background||Identification study||First included in COSMIC|
|Islam et al. 2021 BioRxiv||v3.2|
|Identification||NGS technique||Different variant callers||Multiple sequencing centres|
|Technical validation||Validated in orthogonal techniques||Replicated in additional studies||Extended context enrichment|
|Proposed aetiology||Mutational process||Support|
|Experimental validation||Experimental study||Species|
SBS93 was almost exclusively identified in gastric cancers in the PCAWG dataset, and was also detected on oesophageal squamous cell carcinomas.
Transcriptional strand bias
SBS93 presents transcriptional strand bias for T>C and T>G mutations on TpTpA contexts, with more mutated T than A bases on the untranscribed strands of genes consistent with damage to thymine.