A 45-year-old woman is found to have a germline mutation in the BRCA1 gene. Which of the following molecular functions does BRCA1 primarily serve?

• A It is a proto-oncogene encoding a tyrosine kinase
• B It is involved in homologous recombination repair of double-strand DNA breaks ✓
• C It encodes a transcription factor that activates cyclin D expression
• D It inhibits the RAS-MAPK pathway in epithelial cells

Explanation

BRCA1 is a tumor suppressor gene whose protein product plays a central role in homologous recombination repair of double-strand DNA breaks, working in a complex with RAD51 and BRCA2. Germline heterozygous mutations followed by somatic loss of the second allele (two-hit hypothesis) predispose to breast and ovarian cancers. BRCA2 similarly participates in HR repair; neither encodes a kinase, transcription factor activating cyclin D, nor a RAS pathway inhibitor.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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