Consider a patient with the following clinical findings Fast

Consider a patient with the following clinical findings: Fasting blood glucose level of 25 mg per 100ml (normal 80-100mg per 100ml); feeding the patient glucose results in a rapid elevation of blood glucose level, followed by a normal return to fasting levels; feeding the patient galactose or fructose results in the elevation of blood glucose to normal levels; the administration of glucagon fails to generate hyperglycemia; biochemical examination of liver glycogen reveals a normal glycogen structure Which of the enzyme deficiencies in the glycogen storage diseases described in chapter 12, page 381 of your textbook could account for these clinical findings? Briefly explain how you came to this conclusion. What additional experiments would you conduct to provide a specific diagnosis for this patient?

Solution

6 a the enzyme deficiency involved in this situation is that of glycogen synthase 2 .Glycogen synthase is responsible for converting glucose to glycogen.Glycogen synthase2 is restricted to the liver and serves to maintain blood glucose level during fasting,but in this situation the fasting blood glucose is 25 mg per 100 ml which indicates a deficiency of this enzyme.

b the deficiency of glycogen synthase is characterized by glycogen storage disease type 0.In these patients serum glucose levels are measured to detemine the extent of hypoglycaemia.Serum electrolytes are measured to determine the anion gap.Urine is analysed for the presence of ketone bodies.Liver biopsy is done for definite results.Sequencing of the entire coding region to detect mutation in GSY2 gene .Liver function tests are needed to be done because this condition is associated with mild helatocellular damage along with mild elevation in AST and ALT levels.