To correlate GPR158 expression with clinically, diagnostically and biologically relevant tumour entities [2], we defined oligodendrogliomas (O, n = 83) as IDH mutant, 1p/19q co-deleted tumours, and astrocytomas (A, n = 138) as IDH mutant, ATRX mutant tumours with no 1p/19q codeletion. This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).