B3GNT9 and cancer: Prioritized genes that had not previously been reported as bladder cancer drivers included STAG2, B3GNT9, FAT1 and CDKN1A. We chose STAG2, MLL2/KMT2D and CDKN1A for further replication testing, based on the presence of at least one protein-truncating mutation and the paucity of mutations previously reported in cancers.