What is the Difference Between BRCA1 and BRCA2 Mutation?

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BRCA1 and BRCA2 are both DNA-repair genes that, when mutated, can increase the risk of certain cancers. The main differences between BRCA1 and BRCA2 mutations lie in the types of cancers they are associated with and the extent of the increased risk.

BRCA1 mutations are associated with a higher risk of the following cancers:

  • Breast cancer, including an aggressive form called Triple Negative Breast Cancer
  • Ovarian cancer
  • Pancreatic cancer
  • Prostate cancer

On the other hand, BRCA2 mutations are associated with an increased risk for:

  • Breast cancer
  • Ovarian cancer
  • Melanoma
  • Pancreatic cancer
  • Prostate cancer

Some key differences between BRCA1 and BRCA2 mutations include:

  1. Breast cancer subtypes: BRCA1-associated breast cancers are generally triple negative, meaning they are estrogen receptor negative, progesterone receptor negative, and HER2 negative. In contrast, BRCA2-associated breast cancers are typically estrogen receptor positive.
  2. Ovarian cancer risk: The lifetime risk of ovarian cancer is higher for BRCA1 carriers (40-45%) compared to BRCA2 carriers.
  3. Male breast cancer: Males with BRCA1 mutations have a 1% lifetime risk of developing male breast cancer, while men with BRCA2 mutations have a higher risk of breast and prostate cancer.

It is important to note that not all individuals with BRCA1 or BRCA2 mutations will develop cancer. However, having these mutations does increase the risk of certain types of cancer. Genetic testing is the only way to determine if someone has a BRCA1 or BRCA2 mutation.

Comparative Table: BRCA1 vs BRCA2 Mutation

BRCA1 and BRCA2 are tumor suppressor genes that, when functioning normally, help prevent tumor formation. Mutations in these genes can lead to an increased risk of certain types of cancer. The table below highlights the differences between BRCA1 and BRCA2 mutations:

Feature BRCA1 Mutation BRCA2 Mutation
Cancer Type Associated with triple-negative breast cancer, ovarian cancer, pancreatic cancer, prostate cancer Associated with breast cancer (more often estrogen receptor positive), ovarian cancer, melanoma, pancreatic cancer, prostate cancer
Lifetime Risk 70-80% lifetime risk for breast cancer
50-60% lifetime risk for ovarian cancer
50-60% lifetime risk for breast cancer
30% lifetime risk for ovarian cancer
Men Higher risk of prostate cancer Lower risk of prostate cancer
DNA Repair Deficient in BRCA1-associated cells Capable of carrying out single-strand annealing (SSA) in BRCA2-deficient cells

BRCA1 mutations are more common than BRCA2 mutations and are associated with triple-negative breast cancers, which are more difficult to treat as they don't respond well to hormonal therapies. In contrast, BRCA2-associated breast cancers are more often estrogen receptor positive. Both mutations are associated with an increased risk of ovarian, pancreatic, and prostate cancer, but the lifetime risk for these cancers is higher for BRCA1 mutation carriers.