NTHL1 and breast cancer: To investigate whether heterozygous NTHL1 LoF variants were associated with reduced protein expression and/or altered cellular location in breast cancers as has been observed in gastric tumors18, fluorescent immunohistochemistry was used to measure NTHL1 protein levels, along with an epithelial cell marker (Cytokeratin AE1/AE3), in 8 NTHL1-het breast cancers and 21 sporadic breast cancers.