In contrast to the enrichment of G:C>T:A transversions in MAP, C:G>T:A transitions in NAP, or SBS in PPAP [5, 6, 63, 64], MSH3-related colorectal tumours are characterised by a predominance of small, out-of-frame deletions across the APC gene, further indicating that the mutation profile can provide a hint as to the underlying germline defect. The gene discussed is APC; the disease is colorectal neoplasm.