Immunophenotypic assessment revealed that all MBCs, irrespective of histologic subtype, were of TN phenotype and expressed at least one basal marker, either high molecular weight cytokeratins (CKs), including CK14, CK17, CK5/6, or EGFR10 (Supplementary Tables 1 and 2). Here, KRT17 is linked to maternal uniparental disomy of chromosome 20.