Whereas the evidence for breast cancer being a part of the cancer spectrum of recessively inherited NTHL1 tumor syndrome is strong (Grolleman et al., 2019; Kuiper, Nielsen, De Voer, & Hoogerbrugge, 2020; Rivera, Castellsague, Bah, van Kempen, & Foulkes, 2015), the contribution of NTHL1 p.Q90* heterozygosity, or even homozygosity, to breast cancer incidence in general population requires further investigation. This evidence concerns the gene NTHL1 and neoplastic syndrome.