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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{Rim}}, {{AJL}} {{Alison}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pathophysiology, Pharmacology
|MainCategory=Pathophysiology, Pharmacology
Line 20: Line 20:
|MainCategory=Pathophysiology, Pharmacology
|MainCategory=Pathophysiology, Pharmacology
|SubCategory=Hematology
|SubCategory=Hematology
|Prompt=A 1 year old boy is brought to the pediatrics outpatient clinic for 4 weeks of pallor and excessive sleepiness. His mother reports normal development and feeding habits. Physical exam is significant for hepatomegaly and marked pallor. Blood tests show a hemoglobin of 7.2 g/dL with microcytosis and anisocytosis. Futher testing reveals a mutation in the ALAS2 gene. What is the most appropriate treatment for this patient?  
|Prompt=A 1-year-old male is brought to the pediatrics outpatient clinic for a four week duration of pallor and excessive sleepiness. His mother reports normal development and feeding habits and physical exam is significant for hepatomegaly and marked pallor. Blood tests demonstrate a hemoglobin level of 7.2 g/dL with microcytosis and anisocytosis. Futher testing reveals a mutation in the ALAS2 gene. Which of the following treatments is most appropriate for this patient?  
|Explanation=Sideroblastic anemia is an inherited disease in which the bone marrow produces ringed sideroblasts due to defective hemoglobin synthesis and iron accumulation. Classically, sideroblastic anemia is an X-linked disease although other patterns of inheritance can be encountered. The disease is due to a deficiency in ALA synthase, the rate limiting step in heme synthesis, secondary to a mutation in the ALAS2 gene. This leads to a decrease in heme synthesis and accumulation of non-heme iron around red blood cells giving them the characteristic ringed sideroblasts appearance. Treatment is usually with pyridoxine (vitamin B6) which is a cofactor in the reaction catalyzed by ALA synthase. It is effective in improving the anemia in around 75% of patients.
|Explanation=[[Sideroblastic anemia]] is an inherited disease in which the bone marrow produces ringed sideroblasts, due to defective hemoglobin synthesis and iron accumulation. Most frequently, [[sideroblastic anemia]] is an X-linked disease. The disease manifests due to a deficiency in ALA synthase, the rate limiting step in heme synthesis, secondary to a mutation in the ALAS2 gene. This decrease in heme synthesis leads to an accumulation of non-heme iron around red blood cells, resulting in a characteristic ringed sideroblasts appearance. [[Sideroblastic anemia]] is usually treated with [[pyridoxine]] (vitamin B6), which is a cofactor in the reaction catalyzed by ALA synthase.


|EducationalObjectives= [[Sideroblastic anemia]] is frequently treated with pyridoxine (vitamin B6), a cofactor in the reaction catalyzed by ALA synthase.
|References= Harris JW. X-linked, pyridoxine-responsive sideroblastic anemia. N Engl J Med. Mar 10 1994;330(10):709-11.


Educational objective: Sideroblastic anemia is treated with pyridoxine (vitamin B6) a cofactor in the reaction catalyzed by ALA synthase.
Reference:<br>
Harris JW. X-linked, pyridoxine-responsive sideroblastic anemia. N Engl J Med. Mar 10 1994;330(10):709-11.
|AnswerA=Chronic transfusions
|AnswerA=Chronic transfusions
|AnswerAExp=Chronic transfusions are used to treat patients with thalassemia major or other bone marrow failure syndromes.  
|AnswerAExp=Chronic transfusions are frequently used to treat patients with [[thalassemia major]] or other bone marrow failure syndromes.  
|AnswerB=Deferioxamine
|AnswerB=Deferioxamine
|AnswerBExp=Deferioxamine is used in the treatment of iron overload following chronic transfusions. Although sideroblastic anemia is associated with iron overload, iron chelation is not the first line of therapy.
|AnswerBExp=[[Deferioxamine]] is frequently used in the treatment of iron overload following chronic transfusions. Although [[sideroblastic anemia]] is associated with iron overload, iron chelation is not the first line of therapy.
|AnswerC=Pyridoxine
|AnswerC=Pyridoxine
|AnswerCExp=Pyridoxine or vitmain B6 is a cofactor in the rate limiting step of heme synthesis and it successfully improves the anemia in 75% of patients with congenital sideroblastic anemia.
|AnswerCExp=See explanation.
|AnswerD=Folic Acid and Vitamin B12
|AnswerD=Folic Acid and Vitamin B12
|AnswerDExp=Folic Acid and Vitamin B12 are usually given to treat megaloblastic anemia.
|AnswerDExp=Folic Acid and Vitamin B12 are frequently administered to treat [[megaloblastic anemia]].
|AnswerE=Iron replacement
|AnswerE=Iron replacement
|AnswerEExp=Iron replacement is used to treat patients with iron deficiency anemia.
|AnswerEExp=Iron replacement is frequently used to treat patients with [[iron deficiency anemia]].
|RightAnswer=C
|RightAnswer=C
|WBRKeyword=Sideroblastic anemia, Pyridoxine, Vitamin B6,  
|WBRKeyword=Sideroblastic anemia, Pyridoxine, Vitamin B6, anemia, genetics, X-linked, pattern of inheritance, inheritance, genome, hemoglobin synthesis, pallor
|Approved=No
|Approved=Yes
}}
}}

Revision as of 15:03, 29 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::Pathophysiology, MainCategory::Pharmacology
Sub Category SubCategory::Hematology
Prompt [[Prompt::A 1-year-old male is brought to the pediatrics outpatient clinic for a four week duration of pallor and excessive sleepiness. His mother reports normal development and feeding habits and physical exam is significant for hepatomegaly and marked pallor. Blood tests demonstrate a hemoglobin level of 7.2 g/dL with microcytosis and anisocytosis. Futher testing reveals a mutation in the ALAS2 gene. Which of the following treatments is most appropriate for this patient?]]
Answer A AnswerA::Chronic transfusions
Answer A Explanation [[AnswerAExp::Chronic transfusions are frequently used to treat patients with thalassemia major or other bone marrow failure syndromes.]]
Answer B AnswerB::Deferioxamine
Answer B Explanation [[AnswerBExp::Deferioxamine is frequently used in the treatment of iron overload following chronic transfusions. Although sideroblastic anemia is associated with iron overload, iron chelation is not the first line of therapy.]]
Answer C AnswerC::Pyridoxine
Answer C Explanation AnswerCExp::See explanation.
Answer D AnswerD::Folic Acid and Vitamin B12
Answer D Explanation [[AnswerDExp::Folic Acid and Vitamin B12 are frequently administered to treat megaloblastic anemia.]]
Answer E AnswerE::Iron replacement
Answer E Explanation [[AnswerEExp::Iron replacement is frequently used to treat patients with iron deficiency anemia.]]
Right Answer RightAnswer::C
Explanation [[Explanation::Sideroblastic anemia is an inherited disease in which the bone marrow produces ringed sideroblasts, due to defective hemoglobin synthesis and iron accumulation. Most frequently, sideroblastic anemia is an X-linked disease. The disease manifests due to a deficiency in ALA synthase, the rate limiting step in heme synthesis, secondary to a mutation in the ALAS2 gene. This decrease in heme synthesis leads to an accumulation of non-heme iron around red blood cells, resulting in a characteristic ringed sideroblasts appearance. Sideroblastic anemia is usually treated with pyridoxine (vitamin B6), which is a cofactor in the reaction catalyzed by ALA synthase.

Educational Objective: Sideroblastic anemia is frequently treated with pyridoxine (vitamin B6), a cofactor in the reaction catalyzed by ALA synthase.
References: Harris JW. X-linked, pyridoxine-responsive sideroblastic anemia. N Engl J Med. Mar 10 1994;330(10):709-11.]]

Approved Approved::Yes
Keyword WBRKeyword::Sideroblastic anemia, WBRKeyword::Pyridoxine, WBRKeyword::Vitamin B6, WBRKeyword::anemia, WBRKeyword::genetics, WBRKeyword::X-linked, WBRKeyword::pattern of inheritance, WBRKeyword::inheritance, WBRKeyword::genome, WBRKeyword::hemoglobin synthesis, WBRKeyword::pallor
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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