FISH images confirming the presence of the t(12;15). In 2a, the presence of the ETV6-NTRK3 fusion is demonstrated by the close proximity of a red signal (ETV6 from chromosome 12) with a green signal (NTRK3 from chromosome 15) in each cell. In 2b, each cell shows separation of red and green probes flanking the NTRK3 gene from chromosome 15.