Table 1.

Genome instability phenotypes in base excision repair mutant models.

Gene	Genotype	Phenotype	Genome instability
UNG [27–29]	Ung−/−	Viable B-cell lymphoma Neuronal sensitivity to oxidative damage Neurodegeneration	Uracil accumulation in brain
SMUG [30, 31]	Smugtg/+ Smug/siRNAUng−/−	Viable	C to T mutagenesis
OGG1 [32–35]	Ogg1−/−	Viable UVB-induced skin tumors	8-OHdG accumulation G to T mutagenesis Gamma radiation-induced DSB in OGG1 overexpressing cells
MYH [36, 37]	Myh−/− Ogg1−/−Myh−/−	Viable Reduced survival Lung, ovarian, and lymphoid tumors	Spontaneous mutagenesis G to T mutagenesis
AAG [38–40]	Aag−/−	Viable Sensitivity to alkylation damage Retinal degeneration in +/−	Increased mutagenesis
NTH
[41, 42] [35, 43]	Nth1−/− Ogg1−/−Nth−/− TK6 cell line	Viable	Increased thymine glycol in liver after X-ray irradiation
[44]	Ogg1−/−Nth−/− mice	Viable	Gamma irradiation-induced DSB H2O2 resistant
TDG [45]	Tdg−/−	Embryonic lethal	Deficient repair of mtDNA
MBD4 [46, 47]	Mbd4−/− Mbd4−/−Apcmin/+	Viable Intestinal adenomas	Aberrant chromatin metabolism C to T mutagenesis
FEN [48, 49]	Fen1−/− Fen+/−Apc1638N	Early embryonic lethal Intestinal adenocarcinoma Decreased survival	Microsatellite instability Extensive apoptosis
APE [50, 51] [20]	Ape−/− Ape+/−	Embryonic lethal Sensitive to oxidative stress
[52]	Apex1+/−XPC−/−	Increased UV-induced skin cancer	Increased mutagenicity Papillary adenocarcinoma and lymphoma
XRCC [53, 54]	Xrcc1−/−	Embryonic lethal
[55, 56]	Xrcc1+/−	Increased AOM-induced ACF	SCE in embryo and cell lines
β -Pol [21, 64]	β-Pol−/−	Embryonic lethal	DSB accumulation Increased mutagenesis
[57–60]	β-Pol+/−	Viable Accelerated aging Lymphoma and adenocarcinomas	Increased SCE in MEFs SSB accumulation
LIGI [61]	Lig−/−	Embryonic lethal defective erythropoiesis	Oxidative stress sensitivity Increased mutagenesis Chromosomal aberrations
LIGII [62]	Lig−/−	Embryonic lethal	Elevated SCE