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. 2017 Jun 15;117(3):358–366. doi: 10.1038/bjc.2017.170

Figure 3.

Figure 3

The fate of subclonal KRAS mutations after pre-treatment of tumour DNAs with UDG. DNAs belonging to 12/15 mCRC tumours, resulted subclonally mutated at KRAS by fast COLD-PCR in absence of UDG pre-treatment (UDG- column), had been re-analysed after UDG digestion (UDG+ column), aimed to avoid PCR artifacts due to formalin fixation injuries on DNA molecules. Eighty-three per cent of the mutated (by fast COLD-PCR, UDG-) cases became WT or changed allelic variant after UDG digestion (UDG+), thus demonstrating their artefactual nature. Only in two tumours (17% of the cases) the mutations were re-confirmed after UDG treatment (UDG+). Both mutations had a mutant allele frequency>3%. ND: not determined cases (due to lack of residual DNA).