Children with NF1 are predisposed to CNS tumours typically of pilocytic astrocytoma subtype in the optic pathway, often accompanied by complete inactivation of NF1 through somatic events.42 Grade II gliomas such as diffuse astrocytoma are uncommon in paediatric patients and more frequently associated with TP53 inactivation.43 Intriguingly, somatic TP53 LOH, but not NF1, was observed in our patient’s tumour. The gene discussed is NF1; the disease is neoplasm.