Inflammatory Bowel Disease USMLE Step 1 Practice Question
A 42-year-old woman presents with abnormal uterine bleeding. Vital signs show BP 128/82, HR 88, RR 16, Temp 37.2°C, SpO2 98% on room air. Endometrial biopsy confirms adenocarcinoma. Her father developed colon cancer at 46; paternal aunt had ovarian cancer. Colonoscopy reveals right-sided colon adenocarcinoma with notably few precursor polyps. Serum carcinoembryonic antigen is mildly elevated. She denies diarrhea or abdominal pain. Which genetic mechanism most likely explains her cancer predisposition?
Answer choices
- AChronic ulcerative colitis only
- BMutation in APC with activation of beta-catenin signaling
- CGermline RET activation
- DDefective E-cadherin leading to diffuse gastric cancer
- EMicrosatellite instability due to mismatch repair gene defectCorrect answer
- FBRCA1 mutation with homologous recombination deficiency
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