Homology directed repair

When the homologous DNA is absent, another process called non-homologous end joining (NHEJ) takes place instead.

HDR maintains genomic stability by repairing broken DNA strands; it is assumed to be error free because of the use of a template.

At some later point the DNA ends are processed so that unnecessary residuals of chemical groups are removed and single strand overhangs are formed.

The polymerase is held onto the DNA strand by PCNA (Proliferating Cell Nuclear Antigen).

Multiple ways of "uncoupling" have been suggested, but evidence is not yet sufficient to choose between models (March 2008).

In the budding yeast Saccharomyces cerevisiae homology directed repair is primarily a response to spontaneous or induced damage that occurs during vegetative growth.

[6] During meiosis up to one-third of all homology directed repair events occur between sister chromatids.

The fertility of females and the health of potential offspring critically depend on an adequate availability of high quality oocytes.

During this period of arrest, oocytes are subject to spontaneous DNA damage including double-strand breaks.

However, the oocytes can efficiently repair DNA double-strand breaks, allowing the restoration of genetic integrity and the protection of offspring health.