WBR0423
| Author | [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biochemistry |
| Sub Category | SubCategory::Neurology |
| Prompt | [[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?]] |
| Answer A | AnswerA::Vitamin B1 |
| Answer A Explanation | AnswerAExp::Vitamin B1 is a cofactor of pyruvate dehydrogenase. |
| Answer B | AnswerB::Vitamin B2 |
| Answer B Explanation | AnswerBExp::Vitamin B2 is a cofactor of pyruvate dehydrogenase. |
| Answer C | AnswerC::Vitamin B3 |
| Answer C Explanation | AnswerCExp::Vitamin B3 is a cofactor of pyruvate dehydrogenase. |
| Answer D | AnswerD::Vitamin B5 |
| Answer D Explanation | AnswerDExp::Vitamin B5 is a cofactor of pyruvate dehydrogenase. |
| 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 cofactor of pyruvate dehydrogenase. |
| Right Answer | RightAnswer::E |
| Explanation | [[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. Educational Objective: 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. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::pyruvate dehydrogenase, WBRKeyword::complex, WBRKeyword::vitamin, WBRKeyword::vitamins, WBRKeyword::enzyme, WBRKeyword::deficiency, WBRKeyword::cofactors, WBRKeyword::neurological, WBRKeyword::acetyl-CoA, WBRKeyword::pyruvate |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |