What are genes & how they function
Our bodies are built from instructions in our DNA. Genes are sections of DNA that give directions for how the body forms and functions. Each person inherits two copies of almost every gene — one from each parent. Among many roles, some genes help repair damage to DNA, keeping cells healthy and preventing abnormal growth.
What is BRCA?
“BRCA” stands for BReast CAncer gene. There are two main BRCA genes: BRCA1 and BRCA2.
Everyone has both BRCA1 and BRCA2. These genes normally act to protect cells. They are tumor suppressor genes: their job includes repairing certain types of DNA damage. When they work correctly, they help prevent cancer from developing.
But if one of these genes has a harmful mutation (a change in its DNA that disrupts its function), its ability to repair DNA breaks and restrain abnormal growth is reduced. This increases cancer risk.
BRCA mutations: Who has them & what they do
Mutations in BRCA1 or BRCA2 are relatively rare. About 1 in 400 people (≈ 0.25%) carry a harmful BRCA mutation.
A person who carries such a mutation has greater risk of developing breast cancer, often at a younger age than people without the mutation.
Mutation carriers can also pass the altered gene to their children — each child has a ~50% chance of receiving the mutated gene from a parent who carries it.
Lifetime risk estimates
Here are approximate risks for women carrying BRCA mutations (to age 70) compared with the general population:
| Gene mutation | Approximate risk of breast cancer by age 70 |
| BRCA1 | ~ 55-65 % |
| BRCA2 | ~ 45 % |
| General population (no mutation) | ~ 12 % (≈ 1 in 8 women) |
- Also, people with BRCA1/2 mutations have higher risk of ovarian cancer and possibly other related cancer types.
- BRCA1 mutations are more often linked with aggressive types of breast cancer, such as triple-negative breast cancer.
What to do if you have a BRCA mutation
If genetic testing shows you carry a harmful BRCA mutation, there are several risk-management and prevention strategies. Which choice is right depends on personal & family medical history, preferences, and consultation with healthcare professionals.
Some options include:
- Increased screening (e.g. more frequent mammograms, MRIs).
- Preventive (risk-reducing) medication, such as hormone therapy (e.g. tamoxifen).
- Preventive surgery—such as removal of breast tissue (bilateral prophylactic mastectomy).
- For women who have completed childbearing, removal of ovaries and fallopian tubes (prophylactic salpingo-oophorectomy), since mutations also increase ovarian cancer risk.
Key takeaway
BRCA1 & BRCA2 are important genes whose normal function helps suppress tumors by repairing DNA damage. Mutations in these genes significantly increase cancer risk, but don’t make cancer inevitable. Knowing your BRCA status (if appropriate through family history and genetic counseling) allows you and your healthcare provider to make informed choices for screening and prevention.