EGFR and glioblastoma: Some, like EGFR vI (exon 1–7 deletion) and EGFR vIV (intracellular domain microdeletion), are rare [6, 9, 38, 48], while others like EGFRvII and EGFRvV are marginally more common, each accounting for more than 10 % of all GBM-associated EGFR mutations [20, 28, 32].