DNA damage and breast cancer

Table 2 Summary of DNA lesion type, repair mechanism and gene products

Repair mechanism	DNA lesion type	Genes or gene families involved in repair
NER	Distortions of DNA double helix or bulky adducts	Xeroderma pigmentosum related genes (XPA, XPC and others) and Cockayne’s syndrome related genes (ERCC6 and others)
BER	Small, non-helix-distorting nucleotide base lesions or single strand breaks	AP endonucleases, DNA glycosylases
MMR	Incorrectly paired nucleotides, insertions and deletion loops	MSH2, MLH1
HR	SSB and DSB	BRCA1/2, BRIT1, BLM
NHEJ	Chromosomal breaks, also to create genetic diversity for immune cells	Ku70, Ku80, DNA-PKcs, XRCC4

NER: Nucleotide excision repair; BER: Base-pair excision repair; HR: Homologous recombination; MMR: Mismatch repair; NHEJ: Non-homologous end joining; SSB: Single strand breaks; DSB: Double strand breaks.