Molecular Biology/Genetics USMLE Step 1 Practice Question
A 42-year-old woman presents with vaginal bleeding and is diagnosed with endometrial adenocarcinoma. Vital signs are stable (BP 128/82, HR 78). Her father had colon cancer at age 45, and paternal aunt had ovarian cancer at age 48. Tumor testing reveals microsatellite instability with elevated tumor mutational burden. She denies prior chemotherapy. Which of the following molecular defects involving DNA repair mechanisms is most likely responsible for her malignancy?
Answer choices
- ADefect in UMP synthase
- BMutation in a noncoding mitochondrial tRNA gene
- CMutation in a mismatch repair geneCorrect answer
- DMutation in a nucleotide excision repair gene
- ETrinucleotide repeat expansion
- FBRCA1/BRCA2 syndrome
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