The notion that inactivation of tumor-suppressor gene(s) permits IDH1R132H existence and expression in glioma may account for the continuous presence of IDH1R132H in recurrent gliomas [51, 52], even though some recurrent gliomas underwent genetic deletion of mutant IDH1 allele and copy number alterations [16, 19]. Here, IDH1 is linked to central nervous system cancer.