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Created page with "{{WBRQuestion |QuestionAuthor={{Rim}} |ExamType=USMLE Step 1 |MainCategory=Genetics, Microbiology, Pathology |SubCategory=Neurology |MainCategory=Genetics, Microbiology, Patho..."
 
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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{Rim}}, {{AJL}} {{Alison}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Genetics, Microbiology, Pathology
|MainCategory=Genetics, Microbiology, Pathology
Line 20: Line 20:
|MainCategory=Genetics, Microbiology, Pathology
|MainCategory=Genetics, Microbiology, Pathology
|SubCategory=Neurology
|SubCategory=Neurology
|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?
|Prompt=A 14-year-old male is brought to the physician's office by his mother for a recent-onset headache, vomiting, and ataxia. Following appropriate work-up, the patient is found to have hemangioblastoma in the cerebellum and renal cell carcinomas bilaterally.  Genetic testing leads to a diagnosis.  Which of the following findings is most likely associated with the patient's condition?
|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.
|Explanation=The patient has von Hippel-Lindau (VHL) disease, an autosomal dominant inherited disorder, caused by the deletion of the VHL gene on chromosome 3.  VHL is characterized by hemangioblastomas of the retina, cerebellum, and medulla.  Also patients frequently present with bilateral renal cell carcinomas or other tumors, such as pheochromocytomas.  A common manifestation of VHL in young patients are headaches with neurological symptoms.  Symptoms of other tumors may also manifest, such as hypertension in the case 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).   
The VHL gene product, E3 ubiquitin ligase, which normally targets hypoxia-induced factor (HIF) in the presence of oxygen for destruction, is absent in VHL.  As a result, polycythemia is a finding associated with VHL, due to the overproduction of hypoxia-induced factor (HIF).   


Educational Objective: VHL is associated with polycythemia due to overproduction of HIF
|EducationalObjectives= Polycythemia is associated with VHL, due to an overproduction of HIF.
 
|References= Kaelin WG. The von Hippel-Lindau tumor suppressor gene and kidney cancer. Clin Cancer Res. 2004; 10(18 Pt 2):6290S-5S


Reference: Kaelin WG. The von Hippel-Lindau tumor suppressor gene and kidney cancer. Clin Cancer Res. 2004; 10(18 Pt 2):6290S-5S
|AnswerA=Hematocrit (Hct) = 58 %
|AnswerA=Hematocrit (Hct) = 58 %
|AnswerAExp=Polycythemia is associated with VHL
|AnswerAExp=Polycythemia is associated with VHL.
|AnswerB=Serum sodium = 122 mmol/L
|AnswerB=Serum sodium = 122 mmol/L
|AnswerBExp=Hyponatremia is not commonly associated with VHL.
|AnswerBExp=Hyponatremia is not frequently associated with VHL.
|AnswerC=Serum alanine aminotransaminase (ALT) = 241 IU/L
|AnswerC=Serum alanine aminotransaminase (ALT) = 241 IU/L
|AnswerCExp=Elevated ALT is not commonly associated with VHL.
|AnswerCExp=Elevated ALT is not frequently associated with VHL.
|AnswerD=Platelet count = 43,000 per microliter
|AnswerD=Platelet count = 43,000 per microliter
|AnswerDExp=Thrombocytopenia is not commonly associated with VHL.
|AnswerDExp=Thrombocytopenia is not frequently associated with VHL.
|AnswerE=Serum calcium = 13 mmol/L
|AnswerE=Serum calcium = 13 mmol/L
|AnswerEExp=Hypercalcemia is not commonly associated with VHL.
|AnswerEExp=Hypercalcemia is not frequently associated with VHL.
|RightAnswer=A
|RightAnswer=A
|WBRKeyword=von, hippel, lindau, von hippel lindau, polycythemia, hematocrit, HCT, hemangioblastoma, bilateral, renal, cell, carcinoma, bilateral renal cell carcinoma, headache, vomiting, pheochromocytoma, hemangioblastoma, hypoxia, induced, factor, hypoxia induced factor, HIF, autosomal, dominant, autosomal dominant
|WBRKeyword= von hippel lindau, polycythemia, hematocrit, HCT, hemangioblastoma, bilateral renal cell carcinoma, headache, vomiting, pheochromocytoma, hypoxia induced factor, HIF, autosomal, autosomal dominant, genetics, genes, pattern of inheritance, inheritance, mutation, deletion
|Approved=No
|Approved=Yes
}}
}}

Revision as of 18:52, 31 July 2014
Author [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Genetics, MainCategory::Microbiology, MainCategory::Pathology
Sub Category SubCategory::Neurology
Prompt [[Prompt::A 14-year-old male is brought to the physician's office by his mother for a recent-onset headache, vomiting, and ataxia. Following appropriate work-up, the patient is found to have hemangioblastoma in the cerebellum and renal cell carcinomas bilaterally. Genetic testing leads to a diagnosis. 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 frequently associated with VHL.
Answer C AnswerC::Serum alanine aminotransaminase (ALT) = 241 IU/L
Answer C Explanation AnswerCExp::Elevated ALT is not frequently associated with VHL.
Answer D AnswerD::Platelet count = 43,000 per microliter
Answer D Explanation AnswerDExp::Thrombocytopenia is not frequently associated with VHL.
Answer E AnswerE::Serum calcium = 13 mmol/L
Answer E Explanation AnswerEExp::Hypercalcemia is not frequently 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 the VHL gene on chromosome 3. VHL is characterized by hemangioblastomas of the retina, cerebellum, and medulla. Also patients frequently present with bilateral renal cell carcinomas or other tumors, such as pheochromocytomas. A common manifestation of VHL in young patients are headaches with neurological symptoms. Symptoms of other tumors may also manifest, such as hypertension in the case of pheochromocytoma.

The VHL gene product, E3 ubiquitin ligase, which normally targets hypoxia-induced factor (HIF) in the presence of oxygen for destruction, is absent in VHL. As a result, polycythemia is a finding associated with VHL, due to the overproduction of hypoxia-induced factor (HIF).
Educational Objective: Polycythemia is associated with VHL, due to an overproduction of HIF.
References: Kaelin WG. The von Hippel-Lindau tumor suppressor gene and kidney cancer. Clin Cancer Res. 2004; 10(18 Pt 2):6290S-5S]]

Approved Approved::Yes
Keyword WBRKeyword::von hippel lindau, WBRKeyword::polycythemia, WBRKeyword::hematocrit, WBRKeyword::HCT, WBRKeyword::hemangioblastoma, WBRKeyword::bilateral renal cell carcinoma, WBRKeyword::headache, WBRKeyword::vomiting, WBRKeyword::pheochromocytoma, WBRKeyword::hypoxia induced factor, WBRKeyword::HIF, WBRKeyword::autosomal, WBRKeyword::autosomal dominant, WBRKeyword::genetics, WBRKeyword::genes, WBRKeyword::pattern of inheritance, WBRKeyword::inheritance, WBRKeyword::mutation, WBRKeyword::deletion
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