Question:hard
What is the possible cause for gout in a patient who has a glucose-6-phosphatase deficiency?
What is the possible cause for gout in a patient who has a glucose-6-phosphatase deficiency?
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Trapped glucose-6-phosphate is shunted into the pentose phosphate pathway, raising PRPP and purine and uric acid production.
Updated On: Jul 8, 2026
- Increased synthesis of pentoses
- Increased accumulation of sorbitol
- Increased synthesis of glycerol
- Decreased function of Krebs cycle
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Place the enzyme in context.
Glucose-6-phosphatase deficiency, Von Gierke disease, blocks the final step of turning stored liver glucose-6-phosphate into free blood glucose.
Step 2: Ask where the trapped glucose-6-phosphate goes.
With the exit blocked, glucose-6-phosphate backs up inside the liver cell and gets diverted into other pathways that can still use it, including the pentose phosphate pathway.
Step 3: Connect that pathway to purines.
The pentose phosphate pathway makes ribose-5-phosphate, which feeds directly into making phosphoribosyl pyrophosphate (PRPP). PRPP is the building block the body uses to make new purine bases. More PRPP means more purine synthesis, and purines are broken down to uric acid.
Step 4: Add the clearance problem.
The liver also leans on glycolysis harder since it cannot export glucose normally, which raises lactate. Lactate and uric acid share the same kidney transporter, so high lactate blocks uric acid from being excreted, adding to the buildup.
Step 5: Compare with the other choices.
Sorbitol buildup belongs to a different disorder pattern, seen in diabetes and galactosemia, extra glycerol synthesis is not part of this mechanism, and a slower Krebs cycle does not explain purine overproduction. None of these fit as well as the pentose phosphate route.
Step 6: State the answer.
$\boxed{\text{Increased synthesis of pentoses}}$
The original answer key left this question blank; the choice above follows the accepted biochemical mechanism of high uric acid in Von Gierke disease.
Glucose-6-phosphatase deficiency, Von Gierke disease, blocks the final step of turning stored liver glucose-6-phosphate into free blood glucose.
Step 2: Ask where the trapped glucose-6-phosphate goes.
With the exit blocked, glucose-6-phosphate backs up inside the liver cell and gets diverted into other pathways that can still use it, including the pentose phosphate pathway.
Step 3: Connect that pathway to purines.
The pentose phosphate pathway makes ribose-5-phosphate, which feeds directly into making phosphoribosyl pyrophosphate (PRPP). PRPP is the building block the body uses to make new purine bases. More PRPP means more purine synthesis, and purines are broken down to uric acid.
Step 4: Add the clearance problem.
The liver also leans on glycolysis harder since it cannot export glucose normally, which raises lactate. Lactate and uric acid share the same kidney transporter, so high lactate blocks uric acid from being excreted, adding to the buildup.
Step 5: Compare with the other choices.
Sorbitol buildup belongs to a different disorder pattern, seen in diabetes and galactosemia, extra glycerol synthesis is not part of this mechanism, and a slower Krebs cycle does not explain purine overproduction. None of these fit as well as the pentose phosphate route.
Step 6: State the answer.
$\boxed{\text{Increased synthesis of pentoses}}$
The original answer key left this question blank; the choice above follows the accepted biochemical mechanism of high uric acid in Von Gierke disease.
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