BRCA1— Lots of Mutations, Lots of Dilemmas

Breast cancer is the most common cancer among women in the Western world, with a cumulative lifetime risk of 1 in 8.1 The two strongest risk factors are age and a family history of breast cancer. Five years ago, a region on chromosome 17 was shown by linkage analysis to have a substantial role in early-onset familial breast and ovarian cancer.2 An intense gene-hunting effort of the “positional cloning” type3 culminated in the identification of the BRCA1 gene in the fall of 1994.4,5 These results will require that all physicians who care for patients understand the molecular genetics of . . .