The BRCA1 and BRCA2 Genes
The BRCA1 and BRCA2 (or Breast Cancer 1 and 2) genes are responsible for many cases of familial ovarian cancer and familial breast cancer. Genes are small pieces of DNA, the material that acts as a master "blueprint" for all the cells in your body. Your genes determine such things as what color hair and eyes you have, how tall you are, and what you look like on the inside. They also instruct the body how to build all the chemical substances in your body that keep you running smoothly. Sometimes there is an error in one of your genes that causes it not to do its job properly. This can lead to disease and is called a "genetic defect."
The BRCA1 and BRCA2 genes make a chemical substance that helps your body prevent cancer. Most women have two normal copies of the BRCA1 gene, or BRCA2 gene both of which produce this cancer preventing substance. Some women have a genetic defect in one of their two BRCA1 genes, or BRCA2 genes and don't produce a normal amount of this cancer fighting substance. These women are at very high risk of getting breast or ovarian cancer, as high as 85-90% over the course of a lifetime.
You inherit one copy of each of your genes from your mother, and a second copy of each of your genes from your father. (This is why you look about half like your mother, and half like your father). If one of your parents has a defective BRCA1 gene, or BRCA2 gene, there is a 50% chance you may inherit their defective copy, and a 50% chance you may inherit their normal copy. If you inherit a defective BRCA1 gene, or BRCA2 gene, then each of your children has a 50% chance of inheriting it from you.
Although there is a test to detect a defective BRCA1 or BRCA2 gene, such a test is not recommended for all women . Women with a strong family history of ovarian cancer should consult their physicians about the test.