IDH1 and astrocytoma (excluding glioblastoma): In another study, Wiestler and colleagues defined ‘molecular astrocytoma’, ‘molecular oligodendroglioma’ and ‘molecular glioblastoma’ by combinations of status of IDH1/2, 1p/19q and ATRX immunohistochemical expression and demonstrated that loss of ATRX expression refined classification of anaplastic gliomas by identifying a subgroup of IDH mutated anaplastic astrocytomas with better prognosis [35].