HDAC9 and central nervous system cancer: In summary, HDAC and co-factors gene expression levels discriminate subgroups ofpatients that do not necessarily belong to the same histopathologic grade(e.g. some ODIII cluster with GL tumors, Figure2A) and even within the same grade, molecular subgroups wereidentifiable, which challenges the histopathological classification and mightexplain why all glioma patients do not respond equally to the availabletherapeutic protocols.