NTHL1 and breast cancer: To investigate whether NTHL1-associated breast cancers are driven by the same mutagenesis mechanism as the colorectal cancers from carriers of homozygous mutations1,6, whole-genome sequencing was performed on the breast cancers from the NTHL1-null and NTHL1-het carriers of three different germlines LoF variants (p.(Gln90Ter), p.(Gln287Ter), and p.(Ser22AlafsTer5)), together with nine sporadic breast cancers with no known germline cancer predisposition gene mutations as controls.