IDH1 and central nervous system cancer: We classified gliomas as IDH1/2 mut or IDH1/2 wt, and then designated IDH1/2 mut with high Ki-67 expression as Group 2, IDH1/2 wt with low Ki-67 expression as Group 3, IDH1/2 wt with moderate Ki-67 expression as Group 4, and IDH1/2 wt with high Ki-67 expression as Group 5.