While the functional impact of these alterations in CB and GCT is not understood in detail, data from childhood brain tumors imply that the K27M mutation in H3F3A mutation acts via a dominant negative gain of function by inhibition of the methyltransferase activity of EZH2, thus abolishing Polycomb-mediated repression of numerous genes [22]. Here, EZH2 is linked to granular cell tumor.