Pathways of DNA double-strand break repair and their impact on the prevention and formation of chromosomal aberrations.

DNA double-strand breaks (DSB) are considered the critical primary lesion in the formation of chromosomal aberrations (CA). DSB occur spontaneously during the cell cycle and are induced by a variety of exogenous agents such as ionising radiation. To combat this potentially lethal damage, two related repair pathways, namely homologous recombination (HR) and non-homologous DNA end joining (NHEJ), have evolved, both of which are well conserved from bacteria to humans. Depending on the pathway used, the underlying mechanisms are capable of eliminating DSB without alterations to the original genomic sequence (error-free) but also may induce small scale mutations (base pair substitutions, deletions and/or insertions) and gross CA (error-prone). In this paper, we review the major pathways of DSB-repair, the proteins involved therein and their impact on the prevention of CA formation and carcinogenesis.