lisakb wrote:
It's carried down through the moms. They say that 50% stuff because they really don't want to give out the true stats.
Knockout, I just want to make sure you know this is not correct.

Like all genes, everyone gets one copy from mom, and one from dad.
So, lets say mom has a BRCA mutation.
Mom has two genes, one from her mom, and one from her dad: [BRCA, normal]
When she and your dad's genes combined to make you, then you got one copy from her, and one from your dad. Let's assume dad is NOT a BRCA carrier (but yes, men can and do carry the gene, since it is NOT located on the X chromosome).
So his genes look like this: [normal1, normal2].

So the possible combinations you could have inherited would be:
[normal (from mom), normal1 (from dad)] = no increased risk
[BRCA (from mom), normal1 (from dad)] = increased risk
[normal (from mom), normal2 (from dad)] = no increased risk
[BRCA (from mom), normal2 (from dad)] = increased risk
2 out of 4 possible combinations include BRCA = 50%.

No voodoo or cover up about it. This is why it's really a good idea to see a genetic counselor in addition to a Gyn. They are trained to help you understand what the actual risk profiles look like. Also, your mom's cancer docs should be screening her for BRCA - there will be different treatment choices based on her genetic status. If she is NOT a BRCA carrier, then unless your dad IS, you will not be.