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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}} {{Alison}}
|QuestionAuthor={{YD}} (Reviewed by {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Biochemistry
|MainCategory=Biochemistry
Line 8: Line 8:
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=Neurology
|SubCategory=Neurology
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
Line 20: Line 21:
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=Neurology
|SubCategory=Neurology
|Prompt=A mother brings her 6-month-old male, with neurological symptoms, to the physician’s office following learning that her son has an enzyme deficiency. Upon further work-up, you tell the mother that the deficient enzyme is responsible for the conversion of pyruvate to acetyl CoA.  You instruct the mother to place her child on a ketogenic diet. Which of the following cofactors is not required for the normal function of the enzyme that is deficient in this patient?
|Prompt=A 3-month-old boy is brought by his mother to the physician's office for hypotonia. The mother was recently told that her son's disease may be caused by an enzyme deficiency. Upon further work-up, the physician explains that the deficient enzyme is normally responsible to convert pyruvate to acetyl CoA, and the patient is required to be on a ketogenic diet. Which of the following co-factors is required for the normal functioning of the enzyme deficient in this patient?
|Explanation=[[Pyruvate dehydrogenase deficiency]] is characterized by the inability to convert [[pyruvate]] to [[acetyl-CoA]]. Patients with [[pyruvate dehydrogenase deficiency]] are placed on [[ketogenic]] diets rich in [[lysine]] and [[leucine]], both of which are considered ketogenic amino acids. Pyruvate dehydrogenase contains 3 enzymes that require 5 cofactors for proper functioning: Vitamins B1, B2, B3, B5, and lipoic acid.
|Explanation=[[Pyruvate dehydrogenase deficiency]] is a congenital disease characterized by the inability to convert [[pyruvate]] to [[acetyl-CoA]] and build-up of lactic acid. The patterns of inheritance of pyruvate dehydrogenase deficiency are numerous and several genetic mutations have been implicated. Typically, pyruvate dehydrogenase deficiency manifests with neurological symptoms (cortical atrophy and delayed development and motor skills) that first appear shortly following birth.  Patients with [[pyruvate dehydrogenase deficiency]] are required to be on [[ketogenic]] diets rich in [[lysine]] and [[leucine]], both of which are considered ketogenic amino acids. Pyruvate dehydrogenase contains 3 enzymes that require 5 co-factors for proper functioning: Vitamins B1, B2, B3, B5, and lipoic acid.
 
|EducationalObjectives= [[Pyruvate dehydrogenase deficiency]] is characterized by the inability to convert pyruvate to acetyl-CoA. [[Pyruvate dehydrogenase]] contains 3 enzymes that require 5 cofactors for proper functioning: Vitamins B1, B2, B3, B5, and lipoic acid.
|References= First Aid 2014 page 92
 
|AnswerA=Vitamin B1
|AnswerA=Vitamin B1
|AnswerAExp=Vitamin B1 is a cofactor of pyruvate dehydrogenase.
|AnswerAExp=Vitamin B1 is a co-factor of pyruvate dehydrogenase.
|AnswerB=Vitamin B2
|AnswerB=Vitamin C
|AnswerBExp=Vitamin B2 is a cofactor of pyruvate dehydrogenase.
|AnswerBExp=Vitamin C is a co-factor for dopamine beta-hydroxylase.
|AnswerC=Vitamin B3
|AnswerC=Vitamin B3
|AnswerCExp=Vitamin B3 is a cofactor of pyruvate dehydrogenase.
|AnswerCExp=Vitamin B12 is a co-factor for homocysteine methyltransferase and methylmalonyl-CoA mutase.
|AnswerD=Vitamin B5
|AnswerD=Vitamin K
|AnswerDExp=Vitamin B5 is a cofactor of pyruvate dehydrogenase.
|AnswerDExp=Vitamin K is a co-factor for the carboxylase enzyme that catalyzes carboxylation of glutamic acid residues.
|AnswerE=Vitamin B6  
|AnswerE=Vitamin B6
|AnswerEExp=Vitamin B6 is required for the synthesis of cystathionine, heme, GABA, dopamine, niacin, and histamine. It is not a cofactor of pyruvate dehydrogenase.
|AnswerEExp=Vitamin B6 is required for the synthesis of cystathionine, heme, GABA, dopamine, niacin, and histamine. It is not a co-factor of pyruvate dehydrogenase.
|RightAnswer=E
|EducationalObjectives=[[Pyruvate dehydrogenase deficiency]] is characterized by the inability to convert pyruvate to acetyl-CoA. [[Pyruvate dehydrogenase]] normally contains 3 enzymes that require 5 co-factors for proper functioning: Vitamins B1, B2, B3, B5, and lipoic acid.
|WBRKeyword=pyruvate dehydrogenase, complex, vitamin, vitamins, enzyme, deficiency, cofactors, neurological, acetyl-CoA, pyruvate
|References=First Aid 2014 page 92
|RightAnswer=A
|WBRKeyword=Pyruvate dehydrogenase,Vitamin, Enzyme, Deficiency, Cofactors, Acetyl-CoA, Pyruvate, Hypotonia, Pyruvate dehydrogenase deficiency
|Approved=Yes
|Approved=Yes
}}
}}

Revision as of 19:17, 19 February 2015
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biochemistry
Sub Category SubCategory::Neurology
Prompt [[Prompt::A 3-month-old boy is brought by his mother to the physician's office for hypotonia. The mother was recently told that her son's disease may be caused by an enzyme deficiency. Upon further work-up, the physician explains that the deficient enzyme is normally responsible to convert pyruvate to acetyl CoA, and the patient is required to be on a ketogenic diet. Which of the following co-factors is required for the normal functioning of the enzyme deficient in this patient?]]
Answer A AnswerA::Vitamin B1
Answer A Explanation AnswerAExp::Vitamin B1 is a co-factor of pyruvate dehydrogenase.
Answer B AnswerB::Vitamin C
Answer B Explanation AnswerBExp::Vitamin C is a co-factor for dopamine beta-hydroxylase.
Answer C AnswerC::Vitamin B3
Answer C Explanation AnswerCExp::Vitamin B12 is a co-factor for homocysteine methyltransferase and methylmalonyl-CoA mutase.
Answer D AnswerD::Vitamin K
Answer D Explanation AnswerDExp::Vitamin K is a co-factor for the carboxylase enzyme that catalyzes carboxylation of glutamic acid residues.
Answer E AnswerE::Vitamin B6
Answer E Explanation AnswerEExp::Vitamin B6 is required for the synthesis of cystathionine, heme, GABA, dopamine, niacin, and histamine. It is not a co-factor of pyruvate dehydrogenase.
Right Answer RightAnswer::A
Explanation [[Explanation::Pyruvate dehydrogenase deficiency is a congenital disease characterized by the inability to convert pyruvate to acetyl-CoA and build-up of lactic acid. The patterns of inheritance of pyruvate dehydrogenase deficiency are numerous and several genetic mutations have been implicated. Typically, pyruvate dehydrogenase deficiency manifests with neurological symptoms (cortical atrophy and delayed development and motor skills) that first appear shortly following birth. Patients with pyruvate dehydrogenase deficiency are required to be on ketogenic diets rich in lysine and leucine, both of which are considered ketogenic amino acids. Pyruvate dehydrogenase contains 3 enzymes that require 5 co-factors for proper functioning: Vitamins B1, B2, B3, B5, and lipoic acid.

Educational Objective: Pyruvate dehydrogenase deficiency is characterized by the inability to convert pyruvate to acetyl-CoA. Pyruvate dehydrogenase normally contains 3 enzymes that require 5 co-factors for proper functioning: Vitamins B1, B2, B3, B5, and lipoic acid.
References: First Aid 2014 page 92]]

Approved Approved::Yes
Keyword WBRKeyword::Pyruvate dehydrogenase, WBRKeyword::Vitamin, WBRKeyword::Enzyme, WBRKeyword::Deficiency, WBRKeyword::Cofactors, WBRKeyword::Acetyl-CoA, WBRKeyword::Pyruvate, WBRKeyword::Hypotonia, WBRKeyword::Pyruvate dehydrogenase deficiency
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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