Other mutations that are observed in both subsets of TCC-UB include mutations of phosphoinositide 3-kinase (PI3K, >10%) and deletion of the tumor suppressor genes Tuberous Sclerosis 1 (TSC1, 10%), Patched (PTCH, 40% LOH), CDKN2A, and Deleted in Bladder Cancer 1 (DBC1, 50%) [5, 6]. Here, TSC1 is linked to tarsal-carpal coalition syndrome.