PALB2 and breast cancer: Germline mutations in PALB2 have been identified worldwide (reviewed in [4]), albeit rarely (1–4% of breast cancer families negative for BRCA1/BRCA2 mutations), and these mutations are associated with an increased risk of breast cancer that varies from approximately 2.3 to as high as ~6.0 depending on the mutations being studied and the populations under investigation [5-7].