Mutations in the breast cancer genes BRCA1 or BRCA2 are relatively rare and are predominantly inherited. Mutations in BRCA genes are detected by a simple blood test ordered by your doctor if he or she thinks you are at an increased risk of having the mutation (e.g. due to family history, multiple relatives with breast or ovarian cancer, or early onset of disease). Whether you have or don’t have a BRCA mutation can dictate the way your doctor treats your cancer and also impacts which clinical trials are suitable for you.