What is known about the BRCA1 and BRCA2 genes?
Because family history is the strongest single predictor of a woman’s chance of developing breast cancer, researchers turned to cancer-prone families – those with a high incidence of cancer in several generations – to find specific inherited gene alterations that are passed on from one generation to the next. After a long search, two genes were found that are altered in many families with hereditary breast cancer. The first, BRCA1 (for BReast CAncer gene), was discovered in 1994, and the second, BRCA2, in 1995. The search for other genes continues. Within families with cancer in multiple generations, it had been estimated previously that a woman with an alteration in the BRCA1 gene has about an 85 percent chance of developing breast cancer and a 44 percent chance of developing ovarian cancer by age 70. Prior research in these high-risk families reported that women with BRCA2 alterations have a lower risk of developing both breast and ovarian cancer than women with BRCA1 alterations. Pr