We performed next generation sequencing for the 6 genes of interest (APEX1, PARP1, MSH2, MSH6, MLH1 and PMS2) on multiple specimens from 12 cases with up to 3000x depth of coverage (average = 847x) to definitively determine whether intratumoral heterogeneity exists at this level and thus would confirm the presence of clonal or sub-clonal populations within a tumor. Here, APEX1 is linked to neoplasm.