SSX2B and synovial sarcoma: Although the co-existence of different fusion genes and transcripts have also been reported in synovial sarcoma [23,24], the two fusion transcripts (SS18-SSX2 and SS18-SSX2B) identified for patient P16 likely result from an alignment artifact due to sequence similarity between SSX2 and SSX2B (99.97% BLAST identity), which is supported by the prediction of an identical fusion transcript sequence by FusionCatcher (Table S2).