Nonetheless, actionable key driver mutations are rare in primary brain cancers and frequently analyses yield variants with unclear oncogenic driver potential as illustrated by the example of the two young patients with recurrent H3 K27-altered diffuse midline glioma and FGFR1 mutations (Table 1, Figs. 3A, 5B). This evidence concerns the gene FGFR1 and diffuse midline glioma.