Fig. 3

An example of MSI-H of Case 4 in Table 2. The introduction of this patient refers to the legend of Fig. 2. Electropherogram shows an allelic profile generated from a normal sample (a, b) or from a matching MSH6-deficient tumor sample (c, d) using the MSI detection kit. First, the sex-determination site Amel and the pentanucleotide markers Penta C and Penta D were analyzed. The Amel site and Penta C/Penta D were used to confirm that the tumor sample and the corresponding normal sample were from the same individual. Alleles found in the normal sample should also be present in the tumor sample; otherwise, there may be sample mixing or contamination. In this case, it is advisable to re-extract the sample for testing. The control sample (paraffin-embedded paracancerous tissue) is microsatellite stable (MSS). In this paraffin-embedded tumor tissue (d), a new allele appears compared to the normal sample (b) (new allele peak indicated by the arrow), that is, the mononucleotide repeat markers are unstable. Finally, the results were interpreted by comparing the numbers of changes in the mononucleotide repeat markers in the test samples. Note that additional pentanucleotide alleles of Penta C and Penta D may be present in some MSI-H samples (additional allele peaks indicated by the box are detailed in d)