Identification and validation of VAV1 fusions in PTCL, NOS. (A) Rearrangement of VAV1 and GSS genes as detected in genomic DNA by MPseq. Vertical and oblique black lines represent aberrant read-pairs; blue ends indicate mapping to (+) strand, whereas red ends indicate mapping to (−) strand. (B) VAV1-GSS fusion transcript as detected by RNAseq. Bridging reads spanning the fusion site are shown. TSS, transcription start site. (C) Sanger sequencing of the fusion site in VAV1-GSS fusion. (D) Schematic diagrams of VAV1 protein domains in wild-type VAV1 and resulting from VAV1 fusions. (E) FISH confirming a VAV1 rearrangement in a tumor cell nucleus (blue) from a PTCL, NOS specimen. The normal intact VAV1 allele is indicated by a red-green fusion (f) signal. Disruption of the VAV1 gene region on the other allele is indicated by separation (s) into one red (5′) signal and 1 green (3′) signal. (F) Pathologic features of PTCL, NOS with VAV1 fusion (hematoxylin and eosin stain; inset, CD30 immunostain). Original magnification ×400 (inset, ×1000).