Continuous assessment 2 – PATH20000
Student Name: Michéal O’Flynn
Student Number: 17751871
1. Von Gierke disease
2. Von Gierke disease is caused by a defect in the enzyme glucose 6-phosphatase (G6Pase). G6Pases reductions means glucose-6-phosphate (G6P) is no longer converted to glucose, leading to hypoglycaemia upon fasting. The extra G6P increases the amount of glycogen. The glycogen build-up in the liver would account for the hepatomegaly. The G6P will also convert to pyruvate resulting in an increase in acetyl coA which will inhibit pyruvate dehydrogenase leading to increased pyruvate. The pyruvate will cause a lactate build-up triggering lactic acidosis. The hypoglycaemia will instigate adipose lipolysis which breaks down triacyclglycerols…show more content… Pompe disease is caused by a deficiency in lysosomal acid alpha glycosidase initiating an accumulation of glycogen in the lysosome. However, lysosomal glycogen does not contribute to blood glucose levels and therefore would not result in hypoglycaemia. MCAD disease does cause hypoglycaemia as there is a deficiency in medium-chain acyl Co-A dehydrogenase which engenders a disorder of fatty acid oxidation leading to a reduction in the breakdown of fatty acids into Acetyl CoA. However, acetyl coA is necessary to produce ketone bodies, so it doesn’t account for the ketosis. McArdle’s disease is caused by a deficiency in myophosphorylase causing a glycogen break-down in the muscles. This doesn’t affect glycogen in the liver, so it can’t cause hepatomegaly. Finally, galactokinase deficiency cannot be responsible either. It is caused by a decreased conversion of galactose to galactose 1-phosphate by galactokinase. The only symptom that is reported in children is cataracts due to a build-up of galactitol in the lens of the…show more content… Von Gierke’s is caused by a deficiency in G6Pase which is responsible for the conversion of G6P to glucose. There are two pathways that are impacted by the deficiency glycogenesis and glycogenolysis. The glycogenesis pathway stimulates the synthesis of glycogen from glucose. Without G6Pase glucose cannot be converted to G6P. Glycogenolysis is the break-down of glycerol. This pathway produces glucose however without G6Pase G6P cannot be converted to glucose. These pathways are antagonistically regulated by insulin and glucagon. Insulin is anabolic, it upregulates phosphatases thereby dephosphorylating and activating the glycogenesis pathway, the dephosphorylation conversely inactivates the glycogenolysis pathway. In response to low glucose levels the pancreas will release glucagon which is catabolic and uses the secondary messenger cAMP to phosphorylate enzymes which activates glyogenolysis and inactivates
