WBR0423
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biochemistry |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::A 6 month old male patient with neurological symptoms is brought by the mother to the physician’s office because she was told her son has an enzyme deficiency. Upon further work-up, the physician tells the mother that the deficient enzyme is normally responsible to convert pyruvate to acetyl CoA. The physician instructs the mother that her child is required to be on a ketogenic diet. Which of the following cofactors is not 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 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 recommended to have ketogenic diets or diets rich in lysine and leucine, both of which are considered ketogenic amino acids. Pyruvate dehydrogenase is contains 3 enzymes that require 5 cofactors: 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 is a complex that contains 3 enzymes that require 5 cofactors: Vitamins B1, B2, B3, B5, and lipoic acid. |
| Approved | Approved::No |
| Keyword | WBRKeyword::pyruvate, WBRKeyword::dehydrogenase, WBRKeyword::complex, WBRKeyword::vitamin, WBRKeyword::enzyme, WBRKeyword::deficiency |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |