TRIM25 and posterior fossa ependymoma: Posterior fossa ependymomas lack a signature of recurrent genetic events (Mack et al., 2014), but can be classified according to their epigenetic hallmark into two main groups: group A tumors (EFP‐A) are characterized by the absence of histone H3 K27 trimethylation, whereas group B tumors (EFP‐B) show a high level of trimethylation of histone H3 K27 (Panwalkar et al., 2017).