Subtype‐specific autoantibody repertoires are also demonstrated in patients with breast cancer; autoantibodies to spliceosomes and glycolysis‐related proteins are observed in luminal breast cancer, while autoantibodies to BRCA1, TP53, and cytokeratin‐5/6/14 are often observed in patients with mesenchymal/basal‐like breast cancer. This evidence concerns the gene BRCA1 and breast cancer.