“Overlapping-breakpoint” duplications could be interpreted as an insertion by “paired-end read” methods. The duplication at the breakpoint on chromosome 6 of the t(4;6) in HCC1806 is shown in gray. Paired-end read fragments are shown as black bars joined with a dotted line. The same junction sequences (a, b, c, and d) would be generated by a reciprocal translocation with an “overlapping-breakpoint” duplication (above) or by an insertion of chromosome 6 (gray) into chromosome 4 (black) (below).