We identified AJ individuals with breast and/or ovarian cancer undergoing hereditary breast/ovarian cancer risk assessment since 2006 without evidence of a deleterious mutation on BRCA gene sequencing who were screened for major gene rearrangements in BRCA1 and BRCA2. For each proband, the pre-test probability of identifying a deleterious BRCA mutation was estimated using the Myriad II model. We identified 108 affected individuals who underwent large rearrangement testing (80 breast cancer, 19 ovarian cancer, nine both breast and ovarian cancer).