Phylogenetic trees indicated that the representative patient who had UTUC first and later developed UCB share common ancestral ARID1A and ARID1B mutations, whereas alterations of multiple driver genes, including HRAS, KDR, MYH11, NTRK3, PPARG, RHOB, ZFHX3, and ZFP36L1, occur later (Figure 5A). The gene discussed is ARID1B; the disease is renal pelvis/ureter urothelial carcinoma.