Although only 1–4% RCCs in adults may have TFE3 translocations6,7, TFE3-tRCC constitutes 15% of RCCs in patients <45 years of age and 20–50% of pediatric RCCs8,9. This evidence concerns the gene TFE3 and renal cell carcinoma associated with Xp11.2 translocations/TFE3 gene fusions.