Low grade gliomas (LGGs) and secondary GBMs are excellent examples of this seeing as they commonly harbor mutations in the IDH1 gene which leads to a widespread hypermethylated phenotype termed G‐CIMP.[231] A recent study of LGGs (WHO grade II and III) was able to identify six methylation subtypes M1–M6 which they were able to categorize based on IDH status and tumour type.[232] Mutant IDH1 is a precursor for global methylation changes in gliomas, however WT IDH1 tumours also show methylation changes. The gene discussed is IDH1; the disease is neoplasm.