Jun 19, 2011 04:57PM otter wrote:
rabbit, I'm sorry no one has answered your question yet. I'll give it a try, although I can't answer some of what you asked.
As for the difference between BRCA1 and BRCA2: those are the names of two different genes. Everyone has both of those genes -- the "normal" versions of the BRCA1 and BRCA2 genes are considered "tumor suppressor" genes. They encode products that are used by a cell to help maintain the integrity of the cell's DNA. Problems occur when someone has a mutation in either or both of those genes and the normal "tumor suppressor" products cannot be made.
Here is a very good, thorough explanation of BRCA1 and BRCA2 mutations, and how they relate to breast cancer risk: http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA
This BCO website also has a discussion about BRCA1 and BRCA2, on its "genetics" page: http://www.breastcancer.org/risk/factors/genetics.jsp
It is true that having a mutation in a BRCA gene is associated with a higher risk of developing breast cancer, and of it recurring if already diagnosed. BRCA status (being "BRCA positive", i.e., having a mutation in a BRCA gene) is one of the factors used when deciding what preventive measures would be best (bilateral mastectomy, oophorectomy, etc.).
That's about as much as I know about all this. I can't tell you why there would be a need for a second test. Perhaps someone else in your family has already been tested, and has a known mutation? In that case you would be tested for that specific mutation (abnormal gene sequence) first, because that's quick and fairly inexpensive. If you don't have that precise mutation, they might go back and do a full DNA sequence of your BRCA1 and BRCA2 genes, to see if there is a different mutation. I don't know for sure, though -- I'm just speculating.
I hope you are doing all this through a genetics counselor. He or she ought to be able to give you good answers to these sorts of questions.
My best to you... Be sure to stop by in the "Chemotherapy" forum, so you can find others going through chemo at this same time. It really helps to be able to talk about what you're experiencing.