double-strand break repair via homologous recombination double-strand break repair via synthesis-dependent strand annealing SDSA is a major mechanism of double-strand break repair in mitosis which allows for the error-free repair of a double-strand break without the exchange of adjacent sequences. The broken DNA searches for and base pairs with a homologous region in an intact chromosome. DNA synthesis initiates from the 3' end of the invading DNA strand, using the intact chromosome as the template. Newly synthesized DNA is then displaced from the template and anneal with its complement on the other side of the double-strand break. Reactome:R-HSA-5693554 GO:0045003 biological_process SDSA mitotic gene conversion