Of the four women, three have now had double mastectomies.
"We call ourselves the titless wonders. We are fairly upbeat about it," Ms Brown said.
This week Hollywood star Angelina Jolie announced she had both breasts removed after finding out she carried the gene and was given an 87 per cent chance of getting breast cancer.
Ms Brown had the support of her husband and was in the process of having her last mammogram before her operation when a tumour was found. She had breast cancer.
"It was quite a shock but at the same time it confirmed to me that I made the right decision," she said.
"The tumour was 8mm but it was already a grade 3 so it was quite aggressive. That's why the surgery is so necessary."
Ms Brown said she already accepted she would lose both breasts "so that part of it didn't worry me".
"I accepted the fact I had cancer which three of my family members had and gone through radiotherapy and chemotherapy for. I wasn't looking forward to that part of it."
Ms Brown's older sister who also had the gene was diagnosed with cancer last year and has now had a double mastectomy. Another sister has had both breasts removed - one when cancer was originally found inside and the other after the sisters tested positive.
Ms Brown's three brothers have not been tested "but they are going to be", she said.
Ms Brown said the worst part of carrying the gene was finding out she had passed it on to her son.
Ms Brown is part of a Tauranga Brca support group set up by the Tauranga Breast Cancer Support Service, which she said reflected just how many woman with the gene were out there.
It was not known how many women have tested positive for Brca in Tauranga but support service manager Lea Lehndorf said there were many women with breast cancer they supported who found out afterward they had Brca genes.
Ms Brown said she was happy to offer support to anyone considering being tested for Brca1 or Brca2. She can be contacted at www.breastcancerbop.org.nz.