must not be confused with the t(X;1)(p11.2;q21), also found in renal cell carcinoma

Xp11 translocation renal cell carcinoma (RCCs) harbor gene fusions involving TFE3 transcription factor. The The t(6;11) RCCs harbor a specific MALAT1 (Alpha) - TFEB gene fusion. TFEB and TFE3 belong to the same MiT subfamily of transcription factors. Because of similarities at the clinical, morphologic, immunohistochemical, and genetic levels, the Xp11 translocation RCCs and t(6;11) RCCs are currently grouped together under the category of MiT family translocation renal cell carcinoma.

The identical gene fusion may be found in Xp11 translocation PEComas and Melanotic Xp11 translocation cancers, which differ from the RCC in that they are PAX8 negative and Cathepsin K positive by immunohistochemistry.

TFE3 (transcription factor E3)

Xp11.23

Contains a transcriptional activation domain , a helix-loop-helix, and a leucine zipper; member of the basic helix-loop-helix family (b-HLH) of transcription factors.

SFPQ (PTB-associated splicing factor)

1p34.3

Contains RNA binding domains; involved in pre-m RNA splicing; form complexes with DNA topoisomerase I.

5 SFPQ - 3 TFE3

N-term SFPQ and most of it fused to the DNA binding domains of TFE3 (excluding the acidic transcriptional activation domain, including the C-term helix-loop-helix, and the leucine zipper); no TFE3-SFPQ reciprocal transcript, as the der(X) t(X;1) is missing; the normal TFE3 transcript is found.