In cartilaginous tumors of enchondromatosis patients the IDH1 R132C mutation is more frequent than the IDH1 R132H mutation (70 and 15 %, respectively) [3, 36], while the IDH1 R132H mutation is the most frequent mutation (90 %) in sporadic IDH mutated gliomas [50]. This evidence concerns the gene IDH2 and central nervous system cancer.