RNA sequencing fusion discovery showed fusion junction reads mapped to the exon 30 of CREBBP (16p13.3) and exon 4 of BCORL1 (Xq26.1); results further confirmed by RT-PCR and Sanger sequencing (A,B). The predicted CREBBP chimeric protein reveals the histone acetyltransferase (HAT) domain being retained in the fusion and joined to the C-terminal part of BCORL1 (B). FISH analyses showed CREBBP and BCORL1 break-apart signals (green, telomeric and red, centromeric, arrows, C). BCORL1 on Xq26 shows split-apart of the only allele in this male patient. High BCORL1 mRNA expression (distal to the exon 4 breakpoint) was noted in the CREBBP-BCORL1 positive OFMT, compared to OFMTs with other gene fusions, including MEAF6-PHF1, EP400-PHF1, and ZC3H7B-BCOR (D,E). Additionally full cDNA BCORL1 overexpression was also identified in round cell sarcomas with BCOR-gene abnormalities (BCOR-MAML3 or BCOR ITD) (D).