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Difficulty: MediumNeoplastic Processes

Various hereditary cancer syndromes are characterized by distinct clinical presentations and specific underlying molecular defects. Match each patient's clinical vignette with the fundamental genetic mechanism responsible for their disease pathogenesis.

  • A 35-year-old female (BP 185/115 mmHg, HR 105 bpm) is evaluated for a rapidly enlarging thyroid mass. Physical exam notes oral mucosal neuromas. Labs demonstrate elevated serum calcitonin and 24-hour urine fractionated metanephrines.Constitutive activation of a transmembrane receptor tyrosine kinase
  • An asymptomatic 42-year-old male with normal vital signs undergoes endoscopic screening due to family history. Gastroenterology reports the presence of approximately 300 adenomatous colonic polyps.Failure to degrade a cytosolic transcription factor, resulting in continuous cellular proliferation
  • A 29-year-old female presents with progressive gait ataxia. Vital signs are within normal limits. Neuroimaging identifies a cerebellar hemangioblastoma, while concurrent abdominal ultrasound reveals bilateral renal cysts.Impaired proteasomal degradation of an angiogenic transcription factor under normoxic conditions
  • A 48-year-old female discovers a painless, fixed 3-cm breast mass. Vitals are unremarkable. Pathology confirms triple-negative invasive ductal carcinoma. Her pedigree includes a first-degree relative with high-grade serous ovarian cancer.Defective repair of double-strand DNA breaks leading to genomic instability

Answer

MEN2B (vignette 1) is driven by RET receptor tyrosine kinase activation. FAP (vignette 2) is caused by APC mutation and failure to degrade β\beta-catenin. VHL disease (vignette 3) results from impaired HIF-1 α\alpha degradation. HBOC syndrome (vignette 4) is due to defective homologous recombination DNA repair.
This question requires a two-step reasoning process: first, diagnosing the hereditary cancer syndrome from the clinical vignette, and second, identifying the fundamental molecular defect responsible for that syndrome. The vignettes describe MEN2B (RET mutation), FAP (APC mutation), VHL disease (VHL mutation), and HBOC syndrome (BRCA mutation). Matching these clinical phenotypes to their respective receptor tyrosine kinase activation, Wnt/β\beta-catenin signaling dysregulation, impaired HIF-1 α\alpha degradation, and defective homologous recombination correctly maps the neoplastic processes.

Step-by-Step Solution

1
Analyze the first vignette to diagnose the syndrome and its genetic basis.
The triad of medullary thyroid cancer, pheochromocytoma, and mucosal neuromas diagnoses MEN2B, caused by RET receptor tyrosine kinase activation.
Recognizing the syndromic presentation is the first step to identifying the specific oncogenic driver.
2
Evaluate the second vignette's endoscopic findings.
Hundreds of colonic polyps indicate FAP, which results from APC gene mutation and failure to degrade β\beta-catenin.
FAP has a distinct molecular pathogenesis compared to other polyposis syndromes.
3
Identify the disease described in the third vignette.
Hemangioblastoma and renal cysts are classic for VHL disease, driven by impaired HIF-1 α\alpha degradation.
VHL mutations directly link defective angiogenesis regulation to tumor development.
4
Assess the fourth vignette's family history and pathology.
Triple-negative breast cancer and familial ovarian cancer suggest BRCA mutations, which impair double-strand DNA repair.
BRCA mutations exhibit a characteristic pattern of related malignancies due to genomic instability.

Key Concept

Molecular pathogenesis and genetic drivers of hereditary cancer syndromes
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Topics

Neoplastic Processes

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