Retrospective identification of TFE3-fusion gene mutations by the TCGA project in several patients diagnosed originally with ccRCC or papillary RCC is consistent with the 1–5% incidence of retrospective identification reported among nephrectomy patients by others [2–5] and may be even higher among metastatic RCC patients. This evidence concerns the gene TFE3 and nonpapillary renal cell carcinoma.