YAP1 and ependymoma: Although improved risk models have been proposed in the past dividing tumors according to their cytogenetic patterns into numerical, balanced, or structural subgroups [13], evaluating the presence of individual prognostic factors such as gain of chromosome 1q in PF ependymoma [2, 9, 13, 14], RELA and YAP1 fusions in supratentorial (ST) ependymomas [3, 15–18], or analyzing specific epigenetic patterns [3, 19], none of these have yet been included in stratification of patients enrolled in clinical trials.