Angelina Jolie had both of her breasts removed after testing positive for a BRCA gene mutation.

But what exactly is BRCA? And how do you know if you're at risk?

BRCA is a breast cancer susceptibility gene. All women and men carry the gene. The problem occurs when the gene changes in a harmful way. Harmful BRCA gene mutations have been linked to increases in breast and ovarian cancers.

Watch Difficult Decision for more details on BRCA and how you can find out if you're at risk.