While some of these newly detected mutations (e.g. TP53 and BRCA1) are relatively tissue-nonspecific and could potentially be acquired during clonal evolution of his PC, the FGFR3-TACC3 fusion is extremely rare in PC (Fig. 5 and Supplemental Table 1) and was highly suggestive of a new UC primary. The gene discussed is FGFR3; the disease is pachyonychia congenita.