In view of the small number of patients in some categories, it was not possible to look reliably at all possible interactions within the Cox model, however interaction between IDH1 mutation and tumour grade was specifically examined; Figure 2b shows that, while IDH1 mutations were much more common in AA patients, they were also prognostic for survival, and associated with a similar HR, in GB patients (interaction p > 0.1). The gene discussed is IDH1; the disease is neoplasm.