But keep in mind that the scientists say this mutated gene may be rare.

VOA: special.2009.08.26

If one gene is mutated, a duplicate gene may function in its place.

FORBES: Why You Should Fear Giant Databases With Your DNA

Genentech's breast cancer drug Herceptin works only in women whose cancer has a particular mutated gene.

FORBES: Why Cancer Drugs Need Genetic Testing

At this point, a woman can undergo the more complex genetic test to confirm the presence of the mutated gene.

BBC: DNA spiral