Neoplasia USMLE Step 1 Practice Question
A 42-year-old man with familial adenomatous polyposis presents with abdominal pain, fatigue, and iron-deficiency anemia. Vital signs: BP 128/82, HR 92, RR 16, temp 37.2°C, SpO2 98%. Laboratory studies show hemoglobin 9.2 g/dL and ferritin 18 ng/mL. Colonoscopy reveals hundreds of adenomatous polyps throughout the colon with a malignant mass in the rectum. No extraintestinal manifestations noted. Which genetic mutation explains this syndrome and predisposes to inevitable colorectal cancer progression?
Answer choices
- ABRAF V600E mutation activating the MAPK pathway
- BMismatch repair gene mutations (MLH1, MSH2) causing microsatellite instability
- CReactivation of telomerase through TERT promoter mutation
- DGermline BRCA1/BRCA2 mutations with defective homologous recombination
- EGermline inactivation of the APC tumor suppressor gene leading to constitutive Wnt signaling and polyp formationCorrect answer
- FGermline activation of KRAS oncogene with increased cell proliferation and reduced apoptosis
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.