POLE and exstrophy-epispadias complex: Interestingly, exome sequence analysis revealed four groups of ECs: Group 1, with EEC with mutations in POLE, and showing high mutation rates (ultramutated), associated with good prognosis; Group 2, including EEC with microsatellite instability (hypermutated), and Group 3, tumors including EEC with low copy number alterations, showing similar progression-free survival rates.