In detail, four specific mutations of MLL (g.chr11:118359433C>G, B112; g.chr11:118375263C>G, B71; g.chr11:118375263C>G, B73 and g.chr11: 118348796G>A, W100) exclusively occurred in recurrent bladder cancer samples rather than the primary ones and these mutations belonged to the gain-of-function, different from that of loss-of-function in primary bladder cancers. This evidence concerns the gene KMT2A and urinary bladder cancer.