Genetically, MBCs have a high level of genomic instability, display a complex copy number variation pattern, and tend to harbor significantly more mutations in PIK3CA, WNT, and TP53 compared with TNBCs, as well as presenting loss of CDKN2A and overexpression and amplification of EGFR13–15. This evidence concerns the gene PIK3CA and maternal uniparental disomy of chromosome 20.