IDH1 and glioblastoma: When LGGs were stratified into four subgroups depending on their IDH1 status, 1p19q codeleted status and EGFR status, BICD1 was differentially expressed within the four subgroups, and its expression levels were highest in the subgroup of LGGs with wild-type IDH1 and mutant EGFR, which could be considered to be glioblastoma (grade IV glioma), rather than LGGs (grade II and III gliomas) according to the 2016 WHO classification of CNS tumors (Figure 4C).