Double-strand-break repair model A mechanism proposed for the repair of DNA that has been fragmented at in a non-homologous region. The strands are unwound at the two ends to expose a site of microhomology, a potential pairing of no more than ten bases of each of the two strands. The strands are placed together at the site of microhomology, unpaired bases are cleaved, missing bases are filled in and ligated. Protein factors act to hold together the ends and to catalyse the necessary reactions. The process is closely analogous to the formation of a coding joint in V(D)J recombination of immunoglobulin synthesis.