IDH1 and glioma: The gain of function mutations within the isocitrate dehydrogenase 1 gene (IDH1) are thought to be largely responsible for the glioma hypermethylator phenotype due to the massively increased production of the 2-hydroxyglutarate oncometabolite and have recently been shown to be sufficient to result in a hypermethylator phenotype in glioma cell lines [14,15].