NTHL1 and breast carcinoma: In addition, for 5 of the 8 NTHL1-het cancers, the expression of NTHL1 in the breast cancer cells (AE1/AE3 positive cells) was reduced by >30% compared to the surrounding non-cancer cells (AE1/AE3 negative cells) (Supplementary Fig. 4), while only a small proportion of control cancers showed the same phenomenon (5 of 21), suggesting that NTHL1 expression may be attenuated further specifically in the cancer cells of NTHL1 LoF variant carriers.