Breast cancer diagnosis in a putative obligate gene carrier. A family study.

Hereditary breast cancer is common and accounts for about 8% of all breast cancer. It has a distinctive natural history characterized by early age of onset, excess bilaterality, and vertical transmission consonant with an autosomal dominant inheritance pattern. We describe an informative kindred wherein this knowledge was effectively applied, with resultant high yield: early breast cancer diagnosis in a mother who was a putative obligate gene carrier, and a contralateral breast cancer diagnosis in her daughter. A more intensive stance on breast cancer diagnosis must be employed in members of hereditary breast cancer kindreds who are judged to be at inordinately increased risk. Breast cancer control through application of genetic knowledge is readily achievable in the clinical practice setting.