What genes are involved in breast cancer?
Researchers have discovered several genes contributing to a woman’s susceptibility to breast cancer. We divide them into three groups: • Strong influence, rare occurrence — Women with certain rare genetic disorders have a high risk of developing breast cancer. In other words, the genes for these disorders have a strong influence on breast cancer risk. All told, however, fewer than 1% of breast cancer cases fall in this category. • Strong influence, medium occurrence — This category includes two known genes: the BRCA1 gene on chromosome 17 and the BRCA2 gene on chromosome 13 . Over 200 variations (alleles) for BRCA1 have been discovered and more than 100 for BRCA2. Only some variants of these genes increase the risk of breast cancer. A woman with one of the high-risk variants has an 80% chance of developing breast cancer before age 70. In certain populations, high-risk variants are common. They are found in 2.5% of all Ashkenazi Jews, accounting for over 25% of breast cancer diagnosed
