The function of NTHL1 (nth like DNA glycosylase 1, Ensembl gene identifier ENSG00000065057) is as follows. Bifunctional DNA N-glycosylase with associated apurinic/apyrimidinic (AP) lyase function that catalyzes the first step in base excision repair (BER), the primary repair pathway for the repair of oxidative DNA damage (PubMed:29610152, PubMed:9927729). The DNA N-glycosylase activity releases the damaged DNA base from DNA by cleaving the N-glycosidic bond, leaving an AP site. The AP-lyase activity cleaves the phosphodiester bond 3' to the AP site by a beta- elimination. Primarily recognizes and repairs oxidative base damage of pyrimidines. Also has 8-oxo-7,8-dihydroguanine (8-oxoG) DNA glycosylase activity. Acts preferentially on DNA damage opposite guanine residues in DNA. Is able to process lesions in nucleosomes without requiring or inducing nucleosome disruption. {ECO:0000255|HAMAP-Rule:MF_03183, ECO:0000269|PubMed:10882850, ECO:0000269|PubMed:11328882, ECO:0000269|PubMed:11380260, ECO:0000269|PubMed:11695910, ECO:0000269|PubMed:12140329, ECO:0000269|PubMed:12144783, ECO:0000269|PubMed:12519758, ECO:0000269|PubMed:14734554, ECO:0000269|PubMed:15533839, ECO:0000269|PubMed:17923696, ECO:0000269|PubMed:20005182, ECO:0000269|PubMed:20110254, ECO:0000269|PubMed:21930793, ECO:0000269|PubMed:29610152, ECO:0000269|PubMed:8990169, ECO:0000269|PubMed:9045706, ECO:0000269|PubMed:9705289, ECO:0000269|PubMed:9890904, ECO:0000269|PubMed:9927729}.