WBR0486

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathophysiology, MainCategory::Pharmacology
Sub Category	SubCategory::Hematology
Prompt	[[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?]]
Answer A	AnswerA::Chronic transfusions
Answer A Explanation	AnswerAExp::Chronic transfusions are used to treat patients with thalassemia major or other bone marrow failure syndromes.
Answer B	AnswerB::Deferioxamine
Answer B Explanation	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.
Answer C	AnswerC::Pyridoxine
Answer C Explanation	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.
Answer D	AnswerD::Folic Acid and Vitamin B12
Answer D Explanation	AnswerDExp::Folic Acid and Vitamin B12 are usually given to treat megaloblastic anemia.
Answer E	AnswerE::Iron replacement
Answer E Explanation	AnswerEExp::Iron replacement is 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. 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. Educational objective: Sideroblastic anemia is treated with pyridoxine (vitamin B6) a cofactor in the reaction catalyzed by ALA synthase. Reference: Harris JW. X-linked, pyridoxine-responsive sideroblastic anemia. N Engl J Med. Mar 10 1994;330(10):709-11. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Sideroblastic anemia, WBRKeyword::Pyridoxine, WBRKeyword::Vitamin B6
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::