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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Cancer Discov. 2014 Jun 3;4(8):956–971. doi: 10.1158/2159-8290.CD-13-0879

Figure 1. Genomic complexity of the EGFR locus in glioblastoma cannot be resolved using bulk tumor sequencing.

Figure 1

(A) RNA-Seq data from GBM patient TCGA-19-2624 revealed co-existence of multiple EGFR aberrations including EGFRvII (16% frequency), EGFRvIII (2% frequency), and a G63K mutation (5% frequency); analysis of whole-genome sequencing further revealed the presence of four distinct intragenic rearrangements producing two variants of EGFRvIII and two variants EGFRvII, each with different allelic frequencies as indicated by read counts. (B) The five distinct EGFR aberrations could result in 25=32 possible clone patterns at the cellular level. Two extreme cases are that all five variants are present in all cells (Option 1) or that the five variants each reside in different cells (Option 3); alternatively, the five variants can exist in up to 26 unique combinations at the cellular level (Option 2).