PCR results for previously unreported tandem duplications. The top panel shows the band for the PCR product generated from primers within the duplicated regions (control band), present in both COLO-829 and the NA19141 control sample (since COLO-829 is heterozygous for each duplication). In the bottom panel, the second and fourth lanes show the presence, in the COLO-829 cell line, of the third and fourth, respectively, tandem duplications given in Table 3. Lanes three and five correspond to NA19141. Here forward primers were designed left of the fusion points and reverse primers were designed right of the fusion point, creating an amplicon of about 150 bp straddling the fusion point of the duplication. See Additional file 8: Table S2 for primer sequences.