Although this recommendation reduces the number of 1p/19q tests in IDH‐mutant gliomas, the diagnosis of oligodendroglioma, IDH mutant and 1p/19q codeleted, central nervous system (CNS) World Health Organization (WHO) Grade 2 or 3 still requires the detection of an IDH mutation and a 1p/19q codeletion. Here, IDH1 is linked to central nervous system cancer.