IDH1 and central nervous system cancer: Research on molecular alterations in gliomas has revealed three noteworthy biomarkers, namely codeletion of chromosome arms 1p and 19q (1p/19q codeletion), and mutations in IDH and the TERT promoter, that can be used to classify Grade II-IV gliomas into five principal molecular groups (triple-positive, IDH and TERT mutations, IDH mutation only, triple-negative, and TERT mutation only).