Intratumoral heterogeneity of TP53 and RB1 determined from smMIP sequencing. Tumor BI09 was sectioned into five regions (A to E). Brain tissue grossly uninvolved by tumor was used as a control (X). Each region was assayed for mutations in 33 genes, including TP53 and RB1. This plot shows the allele balance of TP53 and RB1 mutations within each tumor region. Regions A and B have a high allele fraction mutation in TP53, while regions D and E have a high allele fraction mutation in RB1. Sanger results validated TP53 and RB1 mutations in each region and also revealed that all regions shared a R132H mutation in IDH1 (Figure S7 in Additional file 1).