Glycogen storage disease type 0 fructose results in a marked rise in blood lactate levels. Liver biopsy for microscopic analysis and enzyme assay is required for definitive diagnosis. Diagnosis may include linkage analysis in families with affected members and sequencing of the entire coding region of the GSY2 gene for mutations. Histologic analysis of liver tissue demonstrates moderately decreased amounts of periodic acid-Schiff (PAS)–positive, diastase-sensitive glycogen stores. Evidence of increased fat accumulation in the liver may be observed, as in other glycogen-storage diseases. Electron microscopic analysis of liver sections shows normal glycogen structure. Muscle glycogen stores are normal. There are two types of this\\e condition
Glycogen phosphorylase glucose-6-phosphate by the enzyme phosphoglucomutase. Although the reaction is reversible in solution, within the cell the enzyme only works in the forward direction as shown below because the concentration of inorganic phosphate is much higher than that of glucose-1-phosphate. Glycogen phosphorylase can act only on linear chains of glycogen (α1-4 glycosidic linkage). Its work will immediately come to a halt four residues away from α1-6 branch (which are exceedingly common in glycogen). In these situations, a debranching enzyme is necessary, which will straighten out the chain in that area. In addition, the enzyme transferase shifts a block of 3 glucosyl