Although FGFR-fusion positive GBM constitutes a small subset of GBM as a whole (~ 3%), the sheer preponderance of GBM relative to other types of glioma renders this the most common scenario in which FGFR3 fusions will be encountered in most neuropathology practice settings [7, 18, 69]. The gene discussed is FGFR3; the disease is central nervous system cancer.