PPM1D and brain stem glioma: A previous report demonstrated that a similar somatic truncating mutation was also frequent in brainstem glioma, and that PPM1D truncation and TP53 mutation were found mutually exclusively in six and 19 samples, respectively, in 33 brainstem gliomas, whereas PPM1D truncation was detected in only one of 57 cerebral gliomas and was absent in thalamic glioma [55].