34yr old sister had a brca test done. Her results came back as positive for one copy of c.6937+594t> g mutation in brca 2 gene. What does this mean?

? deleterious, now U. The testing report should specify if this is a "deleterious" mutation. If it is, then it is present throughout all her breast tissue increasing her risk of a second/subsequent breast cancer. It also confers a significant risk of ovarian cancer. As a 1st degree relative, you would have a 50% chance of carrying the same mutation and should be tested for this specific mutation.