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 debranching enzyme a glycogen branch down to four glucose residues, it will not remove further residues. Glycogen debranching enzymes assist phosphorylase, the primary enzyme involved in glycogen breakdown, mobilize glycogen stores. Phosphorylase can only cleave α-1,4- glycosidic bond between adjacent glucose molecules in glycogen but branches exist as α-1,6 linkages. When phosphorylase reaches four residues from a branching point it stops cleaving; because 1 in 10 residues is branched, cleavage by phosphorylase alone would not be sufficient in mobilizing glycogen stores. Before phosphorylase can resume catabolism, debranching enzymes perform two functions: Thus the debranching enzymes, transferase and α-1,6- glucosidase converts the branched