**Core Concept:**
BRCA1 is a tumor suppressor gene that plays a crucial role in DNA repair and cell cycle regulation. Mutations in this gene are associated with an increased risk of developing breast and ovarian cancers.

**Why the Correct Answer is Right:**
In BRCA1 positive women, there is a **70% increased risk** of developing breast carcinoma due to the loss of function of the BRCA1 gene. This gene is involved in DNA repair, cell cycle regulation, and maintaining genomic stability. Mutations in this gene lead to the loss of its normal function, resulting in uncontrolled cell growth and increased risk of cancer.

**Why Each Wrong Option is Incorrect:**
A. **30% increased risk**: This is incorrect because the risk is actually higher in BRCA1 positive individuals (70%).
B. **Decreased risk**: This is incorrect because mutations in BRCA1 lead to an increased risk of cancer, not a decreased one.
C. **No risk**: This is incorrect because BRCA1 mutations do increase the risk of cancer, as explained above.
D. **No risk for ovarian cancer**: While BRCA1 mutations increase the risk of breast cancer, they also increase the risk of ovarian cancer.

**Clinical Pearl:**
Understanding the role of BRCA1 mutations in cancer risk is crucial for clinical practice. Physicians should counsel patients with known BRCA1 mutations about their increased risk of breast and ovarian cancers and recommend appropriate screening and preventive measures.