Non homologous end joining is really an error-prone process?

Why is it that non-homologous end joining errors are so common?

NHEJ is a risky repair method. The process doesn't use a complementary template. Therefore, the fusions of blunt-ended DNA duplexes could result in deletions or insertions.

The next question is: How does non-homologous end joining work? The non-homologous ending joining (NHEJ), is a method that repairs DNA double-strand breaks. NHEJ is also known as "nonhomologous" since the break ends can be ligated directly without the use of a homologous template. This contrasts with homology directed repair which requires a homologous sequence.

It is also important to understand why non-homologous end joining is not accurate.

DNA double-strand break (DSBs), which can lead to genetic instability or diversity, are dangerous lesions. Non- homologous - Joining (NHEJ), a well-known DSB repair pathway that has been considered error-prone for a long time. Recent data has shown that NHEJ is extremely precise.

What is error-prone repair?

The SOS response is a global response against DNA damage. It causes the cell cycle to be stopped and DNA repair and mutations are induced. This system is based on the RecA protein (Rad51 for eukaryotes). It is an error-prone repair mechanism that significantly contributes to DNA changes observed across a broad range of species.