Resolution of D-loop Structures through Synthesis-Dependent Strand Annealing (SDSA)

In the synthesis-dependent strand-annealing (SDSA) model of D-loop resolution, D-loop strands extended by DNA repair synthesis dissociate from their sister chromatid complements and reanneal with their original complementary strands, resulting in non-crossover products. SDSA is promoted by the DNA helicase RTEL1. Additional DNA synthesis occurs to fill the remaining single strand gap present in the reannealed DNA duplex. DNA polymerase alpha has been implicated in this late step of DNA repair synthesis, although RTEL1-mediated recruitment of PCNA-bound DNA polymerases may also be involved. The remaining single strand nicks are closed by DNA ligases, possibly LIG1 or LIG3.

Summary from Reactome (R-HSA-5693554), read 2026-09-23.