DDAH1 and nonpapillary renal cell carcinoma: However, eleven genes (CRABP2, DDAH1, TGFA, SPATA18, SCGN, CYP39A1, IL15RA, APOLD1, NTN4, PABPC1L, and SIM2) have not been studied in relation to ccRCC, according to PubMed searches for “GENE and ccRCC”.