Cori's disease is also referred to as type III glycogen storage disease. This is an autosomal recessive disorder, where patients are unable to convert branched glycogen polymers to glucose due to a deficiency of debranching enzyme.
Alpha-1,6 glucosidase or glucosidase is a component of debranching enzyme, and breaks the alpha 1, 6 bond in glycogen. Thus, this enzyme helps mobilize glucose.
Branching bonds of glycogen are essential for effective storage. In Cori's disease, these bonds cannot be broken due to a deficiency in the debranching enzyme.
In this disorder, patients have an inability to convert branched glycogen polymers to glucose. Because limit dextrin is a remaining polymer produced after hydrolysis of glycogen, patients develop limit dextrin accumulation in their cytosol.
While there is glycogenolysis ability in Cori's disease, it is limited due to the inability to breakdown branched glycogen molecules. This limitation in the body's ability to acutely mobilize glucose stores can result in transient hypoglycemia.
Patients have abnormal glycogen accumulation in muscle tissues in Cori disease. The accumulated glycogen is structurally abnormal and impairs the function of muscles, leading to weakness. This side effect of Cori disease is especially pronounced in adult form.
Patients have abnormal glycogen accumulation in Cori disease. This is structurally abnormal and impairs the function of muscles. Often, the first sign and of disease in infants is poor muscle tone, or hypotonia.
Growth is limited because the body cannot mobilize glycogen sufficiently and sustain adequate glucose levels for the body.
Due to the deficiency of the debranching enzyme, there is accumulation of residual glycogen in the liver, which leads to hepatomegaly.
The cells are still able to undergo gluconeogenesis and create free glucose residues, so lactic acid levels are within normal limits.
Unlike in Von Gierke disease, in Cori disease gluconeogenesis is intact. This means that patients are able to generate glucose from non-carbohydrate substances like lactate, glycerol, and glucogenic amino acids.
Patients with Cori disease can develop hepatomegaly from abnormal amounts of accumulating glycogen. If the liver is involved, patients can display elevations in liver function enzymes (LFTs) on lab testing.
The abnormal glycogen accumulation in Cori disease is structurally abnormal and impairs the function of muscles. Additionally, in times of glucose need, muscle protein is metabolized as a glucose source. These factors lead to lab findings of increased creatine kinase, which is a marker of muscle breakdown.
It is recommended to provide frequent daytime feedings, along with continuous nasogastric tube feedings at night to infants up until the age of 3 years old. This is done to ensure they maintain satisfactory blood glucose levels.
Because gluconeogenesis is intact and protein can be used as a source of glucose, patients are recommended to have a high protein diet. A high protein diet prevents breakdown of muscle protein in times of glucose need, preserving muscles.
Uncooked cornstarch is a recommended dietary supplement in patients because it is a slow-release form of glucose.
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