Women diagnosed with breast cancer under age 40 years: The Australian Breast Cancer Family Registry. The majority of breast cancer patients diagnosed before the age of 40 years have no affected family members (zero affected; the "sporadic" breast cancer group), some probands have one affected family member (one affected), and ~8% have a stronger family history (the "familial" breast cancer group). A strong family history is defined as the case proband having two or more first- or second-degree relatives affected by breast or ovarian cancer. x represents the 22 partner and localizer of the breast cancer 2 early onset protein (BRCA2) mutation carriers identified by previous testing in the ABCFR [13, 19]. The filled black stars represent the two probands found to carry PALB2 c.3113G > A who both have a very strong family history of breast cancer. Adapted from Hopper .