BRCA1 and BRCA2 are human genes that belong to a class of genes known as tumor suppressors. Mutation of these genes has been linked to hereditary breast and ovarian cancer.

Three specific mutations, two in the BRCA1 gene and one in the BRCA2 gene, are the most common mutations found in these genes in the Ashkenazi Jewish population. In one study, 2.3 percent of participants (120 out of 5,318) carried one of these three mutations. This frequency is about five times higher than that found in the general population . It is not known whether the increased frequency of these mutations is responsible for the increased risk of breast cancer in Jewish populations compared with non-Jewish populations.

Struewing JP, Hartge P, Wacholder S, et al. The risk of cancer associated with specific mutations of BRCA1 and BRCA2 among Ashkenazi Jews. New England Journal of Medicine 1997; 336(20):1401–1408.

Warner E, Foulkes W, Goodwin P, et al. Prevalence and penetrance of BRCA1 and BRCA2 gene mutations in unselected Ashkenazi Jewish women with breast cancer. Journal of the National Cancer Institute 1999; 91(14):1241–1247.