IDH1 and central nervous system cancer: Based on isocitrate dehydrogenase (IDH) 1/2 mutation status, glioblastomas can also be defined as primary (IDH1/2 wildtype), which originate de novo and secondary (IDH1/2 mutant), which evolve from lower grade gliomas (accounting for 80% IDH1/2 mutant cases) [8].