Prostate, ovarian and breast cancers frequently feature hemizygous deletions of CTCF (Filippova et al, 2002; Damaschke et al, 2020) and loss of one allele of CTCF in kidney and endometrial cancers correlates with poor patient survival (Kemp et al, 2014; Uhlen et al, 2017). This evidence concerns the gene CTCF and breast carcinoma.