The following questions concern individuals that have glycogen storage disease t
ID: 206691 • Letter: T
Question
The following questions concern individuals that have glycogen storage disease type VII (Tarui disease). This disease is a rare autosomal recessive disorder that results from a deficiency in the M (muscle isoform) of phosphofructokinase
Q3. If this patient participates in vigorous exercise, describe how this enzyme defect would impact gluconeogenesis in the liver (or not). In your answer you should clearly define how gluconeogenesis is regulated and the chemical reactions required for this metabolic pathway.
Q4. Would you expect an inhibitor of glycogen phosphorylase to help patients with this disease? Why or why not? You should explain how this inhibitor impacts glycogen metabolism in your answer.
Explanation / Answer
1. In many people phosphofructokinase deficiency is observed and which is further classified into classic, late-onset, infantile and hemolytic. In the classic form, this disease has symptoms of excercise induced muscle cramps,weakness, myoglobinuria as well as hemolytic anaemia etc.
GSD which are present as hepatic involvement mostly result in hypoglycemia, neurotransmitter malfunction.
Phosphofructokinase is the key enzyme that regulates the glycolytic cycle, by converting glucose 6 phosphate to glucose 1, 6 diphosphate, since this enzyme is deficient in GSD VII, therefore improper metabolism takes place affecting the muscles, liver and fibroblasts in the blood. Thus in the biopsy reports of the patients suffering from this disease increased amount of glucose, glucose 6 phosphate , fructose 6 phosphate is observed and fructose 1, 6 diphosphate and triose phosphatases are decreased.
Laforin protein selectively inhibits glycogen phosphorylase.
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