An adolescent male patient came with pain in calf muscles on exercise. On biopsy excessive amount of glycogen present was found to be present in the muscle. What is the most likely enzyme deficiency?
(A) Muscle debranching enzyme (B) Phosphofructokinase I (C) Glucose 6 phosphatase (D) Phosphorylase enzyme
(D) Muscle cramps on exercise is a diagnostic feature of McArdle's disease. In this disease, due to deficiency of muscle glycogen phosphorylase, glycogen stored in muscle cannot be utilized for glucose production causing Muscle cramps and pain on doing strenuous work or exercise. Refer to the table for other symptoms. Type Name Enzyme deficiency Organ Clinical features I Von Gierke's disease Glucose 6-phosphatase Liver , Kidney Glycogen accumulation in liver and kidney Hypoglycemia lactic acidemia ketosis Hyperlipidemia II Pompe's disease Lysosomal alpha-1,4 glucosidase (acid maltase) All organs glycogen accumulation in lysosome in all organ hea is mostly affected* death occur at early age due to hea failure III Cori's disease Amylo alpha-1,6-glucosidase (debranching enzyme) Liver muscles and Hea fasting hypoglycemia hepatomegaly in infancy accumulation of characteristics branched polysaccharides (limit dextrin) muscles weakness IV Anderson's disease Glucosyl 4-6 transferase(branching enzyme) Most tissue A rare disease, glycogen with only few branches accumulate; cirrhosis of liver Death before 5 years of age dur to hea failure or liver failure V McArdle's disease Muscle glycogen phosphorylase Skeletal tissue Muscles glycogen is very high but cannot be used during exercise Cannot perform strenuous exercise Muscles cramps Blood lactate and pyruvate do not increase after exercise VI Her's disease Liver glycogen phosphorylase Liver Liver is increased in size because liver glycogen cannot conve to glucose Mild hypoglycemia and ketosis Good prognosis VII Tarui's disease Phosphofructokinase Skeletal muscles and RBC Muscles cramps due to exercise Blood lactate is elevated Hemolysis occur