For example, pathogenic mutations in the MutY homolog (MUTYH) and NTH1 (a.k.a., NTHL1) DNA glycosylases have been linked to colorectal cancer9,10, while mutations in the uracil DNA glycosylase (UNG) have been associated with the immunodeficiency disorder, hyper-IgM syndrome11. Here, NTHL1 is linked to immunodeficiency disease.