It's a SNP chip and only covers a few common mutations.

To anyone who wants to know for sure whether you're at increased risk of breast cancer, you'll want to get a test that sequences all the known mutations, along with another half-dozen or so genes that can have essentially the same effect as a damaging mutation in BRCA. I'd also urge you to find a genetic counselor, who can help explain the diagnosis in detail, as well as the limitations of the each kind of test.