<p>The study is related to our manuscript entitled "Single-cell genetic heterogeneity linked to immune infiltration in glioblastoma". Using multiplexed FISH analysis of 3-4 tumor cores from 17 glioblastoma formalin-fixed paraffin-embedded (FFPE) tumors, we identified two classes of tumors based on single cell co-occurrence of EGFR and CDK4 amplification. Tumors with a low odds ratio for finding EGFR and CDK4 amplified in the same cell (ORlow tumors) had higher EGFR copy number and higher diversity of copy number in cells harboring EGFR amplification. This suggested that in ORlow tumors EGFR is likely present on extrachromosomal DNA. To test this hypothesis, we performed whole genome sequencing on DNA extracted from FFPE slides from 3 ORlow samples and 3 ORhigh samples and used AmpliconArchitect to investigate the structure of the EGFR amplicon. We found multiple breakpoints and high complexity structure in the 3 tested ORlow samples, but not in the ORhigh samples, supporting the possibility of an extrachromosomal nature of EGFR amplification in the first group.</p>

Whole-Genome Sequencing Analysis of Extrachromosomal DNA with Amplicon    Architect

Glioblastoma study with WGS data on dbGaP (6 participants)