Direct-to-consumer advertisements are urging women to be tested for mutations in BRCA1 and BRCA2 genes, which are the most common known causes of an inherited predisposition to breast and ovarian cancer. Clinically important BRCA mutations have been found in about 2% of Ashkenazi Jewish women, and are estimated to occur in about 1 in 300 to 500 women in the general non-Jewish US population. The prevalence appears to be lower in non-whites.