Any immediate female relatives should be tested - sisters, aunts, first cousins - on the fathers side as well as the mutation can come from either parent. It's important to know who is positive for the mutation because risk of cancer is so much higher.

Should be noted that it's tougher in the U.S. because in some states they deny people insurance when they test positive, which stops some women from testing at all. Crazy and sad. Not an issue here in Canada as far as I know

I would inform them and let them decide what to do

I also went to a genetic counselor and she said that the family pattern is just as important as a genetic test. But also my doctor said that she had a few patients who were well into their 70's that have the BRCA mutation..its not a for sure --you just never know what triggers these cancer cells.

yes I think everyone-cousins too. I have a genetic mutation (ATM gene) and I informed all my cousins. Some did the testing some did not. People have different philosophies and that's ok-but anyone in my family I let them know so they can get better testing and more aggressive testing of breast and colon. Helps if insurance company knows all the information so they don't hold up any process.