Briefly, employing array-based and sequencing methodologies, four major EC groups were characterized: (i) ultramutated cancers with DNA polymerase epsilon (POLE) mutations (7%), (ii) hypermutated cancers with MSI due to MLH1 promoter methylation (28%), (iii) ECs with low mutation rate and low frequency of DNA copy-number alterations (CNA, 39%) and (iv) ECs with low mutation rate but high-frequency DNA CNA (26%) (Kandoth et al., 2013). The gene discussed is POLE; the disease is cancer.