Fusion of a novel gene, RCC17, to the TFE3 gene in t(X;17)(p11.2;q25,3)-bearing papillary renal cell carcinomas

A subset of childhood and young adult renal cell carcinomas displays a recu rrent translocation t(X;17)(pll;q25) as the sole cytogenetic abnormality. I n two young girls, we demonstrate that this translocation results in the fu sion of a novel gene, designated RCC17, at chromosome 17q25, to the transcr iption factor TFE3 located on the Xp11 chromosomal region. In both cases, t he t(X;17) fuses the NH2-terminal region of RCC17 to the COOH-terminal part of TFE3 including the basic helix-loop-helix DNA-binding domain and the le ucine zipper dimerization domain. The reciprocal fusion transcript TFE3/RCC 17 is also expressed. RCC17 encodes a putative protein of 553 amino acids. It is ubiquitously expressed in normal adult tissues. No significant simila rity was found with other fusion partners of TFE3 or with any relevant func tional protein domains, precluding informed speculation about the normal fu nction of this gene.