BRCA genes (Familial Breast Cancer)
🧬 BRCA gene mutations increase the risk of several cancers but do not guarantee their development. These mutations impair DNA repair, leading to accumulation of genetic errors and a higher likelihood of malignancy.
📖 About
- ☑️ Around 5–10% of breast cancers are caused by inherited mutations.
- 🧬 BRCA1 and BRCA2 are tumour suppressor genes involved in DNA repair.
- Inheritance is autosomal dominant – only one faulty copy is needed to raise cancer risk.
- BRCA mutations greatly increase the lifetime risk of breast and ovarian cancer, and also affect other sites.
- BRCA1: ↑ risk of breast, ovarian, and pancreatic cancers.
- BRCA2: ↑ risk of breast, ovarian, pancreatic, prostate cancer, and melanoma.
- Some people choose risk-reducing surgery (bilateral mastectomy, oophorectomy) to lower risk.
👪 Inheritance and Risk
- Autosomal Dominant: One copy of the mutated gene from either parent is sufficient.
- 📊 A carrier has a 50% chance of passing it on to children.
- 🎀 Women with BRCA mutations:
- Breast cancer risk: 60–80%
- Ovarian cancer risk: 15–45%
- 🧔 Men with BRCA2 mutations: ↑ prostate cancer risk (~20% lifetime).
- ➡️ Not everyone with BRCA mutations develops cancer, but risk is many times higher than general population.
🎯 Associated Cancers
- 🎀 Breast cancer – both men & women.
- 🥚 Ovarian cancer – especially in BRCA1 carriers, often late diagnosis.
- 🍐 Prostate cancer – more common in BRCA2 carriers.
- 🍎 Pancreatic cancer – risk increased with both BRCA1 and BRCA2.
- 🌞 Melanoma – linked to BRCA2 mutations.
🧪 Genetic Testing & Screening
- 🧾 Genetic testing offered to those with strong family history of breast/ovarian cancer.
- 🔍 Enhanced screening:
- Earlier & more frequent mammograms
- Breast MRI (higher sensitivity in younger women)
- 🩺 Prophylactic surgery – mastectomy, salpingo-oophorectomy significantly reduce risk.
⚕️ Management & Prevention
- 🔪 Risk-reducing surgery: Bilateral mastectomy, salpingo-oophorectomy.
- 💊 Medication: Tamoxifen or raloxifene may reduce breast cancer risk.
- 🏃 Lifestyle: Healthy weight, ↓ alcohol, physical activity may help reduce risk.
- 👶 Family planning: Preimplantation genetic diagnosis (PGD) with IVF can prevent passing mutations to children.
💭 Emotional & Psychological Impact
- 😟 Positive BRCA test → anxiety & difficult decisions about surgery, surveillance, and family planning.
- 💬 Genetic counselling is essential before and after testing.
- 🤝 Support groups provide psychological support and shared experiences.
💡 Exam Pearls
- 🔑 BRCA mutations = autosomal dominant tumour suppressor gene defect.
- 🎀 Key association = early-onset breast & ovarian cancers.
- 📊 NICE: women with BRCA should be offered MRI screening from age 30.
- 👨 Men with BRCA2 mutation – think prostate cancer risk.
