Fig. 1

Example of a simple structural variant that illustrates how the signatures of fusions are defined. The horizontal structure in the middle represents the double-stranded DNA of a chromosome. Two read pairs are depicted as horizontal arrows mapping to the positive and negative strand of the DNA (the reads in the pairs are enumerated as pxry — pair x, read y). Assuming that the insert size of the two pairs are significantly above their expected value, an SV caller would call a deletion event from the two read pairs. The two dashed vertical lines indicate two breakends in the DNA. The breakends are connected by an arrow labelled “fusion”, which corresponds to the deletion event. The orientation signature of the fusion is indicated as “+” and “−“next to the breakends according to the mapping orientation of the reads that constitute the evidence to the fusion call