In 2009, Yan's study indicated that mutations of IDH1 and IDH2 occurred in majority of several types of malignant gliomas and reported the incidence of IDH1/2 mutation in diffuse astrocytoma (90%), anaplastic astrocytoma (73%) primary GBM (5%) and secondary GBM (85%). The gene discussed is IDH1; the disease is malignant glioma.