IDH1 and pilocytic astrocytoma: The diffuse astrocytoma in this patient lacked alterations in TP53, IDH1, and IDH2. Instead, the additional cooperating mutations involved PTPN11 and NF1. Amongst sporadic gliomas, PTPN11 mutations are rare and most commonly found in pilocytic astrocytomas, whereas NF1 mutations are very common in primary glioblastomas but not typically seen in diffuse lower-grade astrocytomas [19, 20, 21].