YAP1 and ependymoma: Among supratentorial ependymomas, DNA methylation profiling identified three molecular subgroups, namely “EPN, RELA” (72%) including all cases harboring RELA fusions, “EPN, YAP” (11%) including cases harboring YAP fusions and “SUBEPN, ST” (17%) for which no gene fusions or other driver genes have been identified yet 17.