Figure 2.

Different types of double-strand exchange. Via HDR (or NHEJ between two DSBs) the outcome of double-strand exchanges can be a SCE (A), a meiotic cross-over or a homologous translocation (B), a symmetric (C) or asymmetric (D) heterologous reciprocal translocation, an inversion (E) or a ring chromosome plus a fragment (F). A centric ring chromosome results after replication and odd numbers of SCEs in double-sized dicentric rings (G), which are unstable, due to bridge formation, and disrupted during nuclear division (see Figure 3).