PMC5871904_01
Diffuse intrinsic pontine glioma cross-sections at autopsy and MRI. a Histopathological specimens, showing six equal cross-sections of tumor A-F progressing from superior to inferior sections, with one of six quadrants in each cross-section used for sequencing. b Brain MRI (T1 plus contrast) axial images, progressing from superior to inferior sections, demonstrating primarily unilateral necrosis and corresponding contrast enhancement
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Fig1
The involved brainstem was sectioned into six cross-sections (superior to inferior, Fig. 1). We integrated these and the other (sub-clonal) mutations alongside copy number variants (CNVs) (Supplementary Fig. 1), which significantly informed a representative DIPG tumor evolution map (Fig. 2b).
Tumor sequencing and copy number analysis reveal clonal events and tumor evolution. a Overall, 61 mutations were noted in the five sequenced tumor samples with five mutations seen in all samples, and previously identified cancer consensus mutations in red ("A1" corresponds to "A1" quadrant in Fig. 1a, etc.) b Tumor evolutionary map displays distance corresponding to degree of mutational and copy number alterations. HIST1H3B, ACVR1, and PTEN are conserved in all five specimens. c Candidate pathway genes with conserved CNVs and corresponding expression changes by RNA sequencing
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Fig2
Whole exome sequencing revealed 61 somatic mutations distributed throughout the five tumor sites (Fig. 2a), including point mutations in HIST1H3B (p.K27M), ACVR1 (p.G328V), and PTEN (p.Q97X), and copy number loss of PTEN in all five samples. Several genes were found to have corresponding CNV and RNA level changes, including nine genes with copy number gain and overexpression and seven genes with copy number loss and reduced expression, including PTEN and multiple genes of unclear significance in DIPG pathogenesis (Fig. 2c). An immunostain for Ki-67 showed marked heterogeneity from region to region (Supplementary Fig. 2).