Mutations in Mismatch Repair (MMR) associated genes (MSH2, MSH6, MLH1 and PMS2) producing Microsatellite Instability or mutations in proofreading polymerases epsilon and delta (POLE and POLD1) show a low prevalence in bladder carcinomas ranging from 2.2% for MLH1 and POLD1 to 6.1% for POLE. The gene discussed is MSH2; the disease is urinary bladder carcinoma.