It is widely thought that C-NHEJ is also error-prone, because the repair process involves processing of the DNA ends at the break sites, which can lead to nucleotide deletion. Hence, joining of such DNA ends via C-NHEJ in the transcribed region could be mutagenic and/or lethal for cells.

Why is NHEJ considered an error prone mechanism?

Importantly, NHEJ is an error-prone repair pathway. Because the process does not use a complementary template, the fusion of the blunt-ended DNA duplexes may result in deletion or insertion of base pairs.

Is homologous recombination error prone?

Homologous recombination (HR) is an evolutionarily conserved process that plays a pivotal role in the equilibrium between genetic stability and diversity. HR is commonly considered to be error-free, but several studies have shown that HR can be error-prone.