For tumor types with global hypomethylation or hypermethylation (such as pituitary tumors or isocitrate dehydrogenase (IDH)-mutant glioma (GLM), respectively) or low tumor purity because of a complex tumor microenvironment, such as mesenchymal IDH wild-type glioblastoma (GBM)29, it might introduce a class-specific bias that remains to be investigated systematically. The gene discussed is IDH3A; the disease is pituitary tumor.