Although fructose-1,6-bisphosphatase (F1,6BPase) deficiency can lead to infant mortality due to severely impaired gluconeogenesis, beyond childhood afflicted individuals develop hypoglycemia usually only associated with fasting or febrile infections. Given the role of F1,6BPase in overall carbohydrate metabolism, which of the following metabolites would be expected to increase in the plasma of these patients following depletion of hepatic glycogen stores?

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Quizplus · Accepted Answer

In F1,6BPase deficiency, gluconeogenesis is impaired, leading to an accumulation of glycolytic intermediates like lactate, especially during fasting or stress when gluconeogenesis is needed to maintain blood glucose levels. During normal hepatic gluconeogenesis the major substrates for glucose synthesis are alanine, pyruvate, and lactate. Defective F1,6BPase would restrict the flow of alanine and lactate conversion to pyruvate and the subsequent input of pyruvate into gluconeogenesis. The net effect would be a significant increase in circulating levels of lactate.

Although Fructose-1,6-Bisphosphatase (F1,6BPase) Deficiency Can Lead to Infant Mortality Due