MGMT and neoplasm: Important markers of altered methylation in both paediatric and adult tumours include DNA‐5‐hydroxymethylcytosine (5hmC), levels of which increases with tumour progression, CpG island methylator phenotype (G‐CIMP), a hallmark prognostic marker of paediatric and adult tumours and MGMT promoter hypermethylation, observed in most gliomas and is an excellent indicator of TMZ resistance, especially in GBM.113