WBR0544
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Genetics, MainCategory::Microbiology, MainCategory::Pathology |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::A 14 year old boy is brought by his mother to the physician's office for recent-onset headache, vomiting, and ataxia. The patient is previously healthy; he takes no medications and has no allergies. Following appropriate work-up, the patient was found to have hemangioblastoma in the cerebellum and renal cell carcinomas bilaterally. Requested genetic testing is ordered and the diagnosis is made. Which of the following findings is most likely associated with the patient's condition?]] |
| Answer A | AnswerA::Hematocrit (Hct) = 58 % |
| Answer A Explanation | AnswerAExp::Polycythemia is associated with VHL |
| Answer B | AnswerB::Serum sodium = 122 mmol/L |
| Answer B Explanation | AnswerBExp::Hyponatremia is not commonly associated with VHL. |
| Answer C | AnswerC::Serum alanine aminotransaminase (ALT) = 241 IU/L |
| Answer C Explanation | AnswerCExp::Elevated ALT is not commonly associated with VHL. |
| Answer D | AnswerD::Platelet count = 43,000 per microliter |
| Answer D Explanation | AnswerDExp::Thrombocytopenia is not commonly associated with VHL. |
| Answer E | AnswerE::Serum calcium = 13 mmol/L |
| Answer E Explanation | AnswerEExp::Hypercalcemia is not commonly associated with VHL. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::The patient has von Hippel-Lindau (VHL) disease, an autosomal dominant inherited disorder caused by the deletion of VHL gene on chromosome 3. It characterized by hemangioblastomas of the retina, cerebellum, and in the medulla. Also patients frequently have bilateral renal cell carcinomas, and other tumors such as pheochromocytoma. The most common presentation of VHL is headaches with neurological symptoms in a young patient - childhood, adolescence, or early adulthood. Symptoms of other presenting tumors may also be present, such as hypertension in the case of development of pheochromocytoma.
VHL gene product, E3 ubiquitin ligase, that normally targets hypoxia-induced factor (HIF) in the presence of oxygen for destruction, is absent in VHL. As a result, polycythemia is an associated finding in VHL due to the overproduction of hypoxia-induced factor (HIF). Educational Objective: VHL is associated with polycythemia due to overproduction of HIF Reference: Kaelin WG. The von Hippel-Lindau tumor suppressor gene and kidney cancer. Clin Cancer Res. 2004; 10(18 Pt 2):6290S-5S |
| Approved | Approved::No |
| Keyword | WBRKeyword::von, WBRKeyword::hippel, WBRKeyword::lindau, WBRKeyword::von hippel lindau, WBRKeyword::polycythemia, WBRKeyword::hematocrit, WBRKeyword::HCT, WBRKeyword::hemangioblastoma, WBRKeyword::bilateral, WBRKeyword::renal, WBRKeyword::cell, WBRKeyword::carcinoma, WBRKeyword::bilateral renal cell carcinoma, WBRKeyword::headache, WBRKeyword::vomiting, WBRKeyword::pheochromocytoma, WBRKeyword::hemangioblastoma, WBRKeyword::hypoxia, WBRKeyword::induced, WBRKeyword::factor, WBRKeyword::hypoxia induced factor, WBRKeyword::HIF, WBRKeyword::autosomal, WBRKeyword::dominant, WBRKeyword::autosomal dominant |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |