Ashkenazi genes and breast cancer

Most women of Ashkenazi Jewish descent should be tested for the most common genetic mutations that cause breast and ovarian cancer, Canadian researchers have found. About 1% of the women they tested had a mutation in either the BRCA1 or BRCA2 gene, which carries a very high risk of cancer. Women with the mutated BRCA1 gene have a lifetime risk of breast cancer of about 70% and a 30%-40% risk of ovarian cancer. Those with a mutated BRCA2 gene have a 50% risk of breast cancer and a 20% risk of ovarian cancer. The defective genes occur in about 2.5% of the Ashkenazi Jewish population. Ashkenazi Jews account for an estimated 80% of the world's Jews and have a very high incidence of certain genetic diseases, including Tay-Sachs, Niemann-Pick, Gaucher and Canavan diseases, Bloom Syndrome and Fanconi anemia.