Our analysis underscores the vast genetic heterogeneity of bladder and urothelial carcinomas, with frequent mutations identified in widely recognized driver genes such as TP53 (51.9%), TERT (42.9%), KDM6A (28.6%), KMT2D (27.4%), and ARID1A (26.5%), as well as notable copy number alterations including deletion of CDKN2A/B and amplification of CCND1 and MDM2. The gene discussed is KMT2D; the disease is urothelial carcinoma.