This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
Congenital lactic acidosis occur due to the deficiency of which of the following enzyme? 
Select and explain. 
A. Transketolase, B. Pyruvate dehydrogenase enzyme complex, C. Pyruvate kinase, D. Pyruvate decarboxylase
B: Pyruvate dehydrogenase enzyme complex
Answer: B: Pyruvate dehydrogenase enzyme complex 
Explanation: Inherited pyruvate dehydrogenase deficiency, presents with lactic acidosis. Due to lack of pyruvate dehydrogenase,there will be lack of Acetyl co A production and pyruvate to lactate conversion occurs leading to accumulation of lactic acid Causes of lactic acidosis: 1. Tissue hypoxia 2. Mitochondrial disorders 3. Deficiency of: PDH Enzyme TCA cycle enzymes Vit B1 4. Poisoning : Cyanide, Mercury, Arsenite Reference: Harper's Illustrated Biochemistry 30th Edition Page no: 174