Figure 4.

DSB repair and synthesis-dependent strand-annealing recombination model for minisatellite instability. Protruding single-strand ends formed by staggered nicks in a minisatellite allele can either anneal together out of register, producing an intra-allelic duplication after synthesis and ligation, or can invade the allelic partner. Most strand-invasion events are aborted, either before or, in a minority of cases, after synthesis extends into the minisatellite flanking DNA (depicted here). Reinvasion and synthesis at another location in the template allele frequently occur. Ultimately, extended strands anneal together out of register, single-strand gaps are filled in, and heteroduplexed regions are repaired. In a minority of cases, the extension process is not aborted, and Holliday junctions are formed and further resolved as either crossover products (depicted here) or simple conversion events.