In the WHO classification, with a list of RCC defined molecularly, including TFE3-rearranged RCC, TFEB-rearranged RCC, ELOC (TCEB1)-mutated RCC, Fumarate hydratase (FH)-deficient RCC, Succinate dehydrogenase (SDH)-deficient RCC, ALK-rearranged RCC, SMARCB1-deficient RCC, and so on (3), a molecular perspective to define RCC is necessary. The gene discussed is TFE3; the disease is renal cell carcinoma.