Epigenetic inactivation of tumor supressor genes is critical to the pathogenesis of cancers and some DNA methylation biomarkers, e.g. RASSF1A, are known to be methylated in several different tumor types, i.e. lung, breast, prostate, glioma, neuroblastoma and kidney cancer (for review: [30,31]). The gene discussed is RASSF1; the disease is glioma.