IDH1 and central nervous system cancer: IDH2 mutations were found in 0.5 % of pGBM (1/215), 3.4 % of sGBM (1/29) and 2.8 % (16/577) of low grade gliomas, while IDH1 mutations are found in 14.1 % (29/205) of pGBM, 55.2 % (16/29) of sGBM and 69.8 % (403/577) of low grade gliomas.