Researchers from the University of Manchester in England revealed that women who come from families with BRCA2 mutations are still at a greater risk for developing breast cancer – even if they test negative for the BRCA2 gene themselves, Fox News reports.

The BRCA genes produce tumor suppressor proteins that help repair damaged DNA, so when these genes are faulty, genetic damage can accumulate in the body.

Recently, Angelina Jolie had undergone a double mastectomy after testing positive for a mutation in the BRCA1 gene.  She also noted that the mutation meant that her risk of developing breast cancer was 87 percent. But according to study author Dr. Gareth Evans, her risk had a much wider degree of variability.

According to Evans, there are approximately 77 single nucleotide polymorphisms (SNPs) that women can inherit, which have been identified as contributing  to their breast cancer risk, and the wrong combination of these SNPs can greatly enhance their chance of developing disease.

“So even though you may test negative for the fault in BRCA1 and BRCA2 you may still inherit a bad combination of these other factors,” Evans said. 

In order to verify this, Evans and his team analyzed 807 BRCA families and identified 49 women who tested negative for their family-specific BRCA mutation – but still went on to develop breast cancer.

“So if you’re a first degree relative in a family with a BRCA2 mutation, and you have two close relatives with breast cancer at a young age, you should still be considered at moderate to high risk for developing breast cancer,” Evans sad.