Glycogen Storage Disease Type III (GSD III), also referred to as Cori disease or Forbes disease, is a rare genetic disorder characterized by the impaired metabolism of glycogen, a form of stored glucose, in the body. This autosomal recessive disorder is caused by a deficiency of the enzyme glycogen debranching enzyme (GDE), which plays a crucial role in breaking down glycogen into glucose.
Individuals with GSD III exhibit a range of symptoms that vary in severity. Common symptoms include enlarged liver, low blood sugar levels (hypoglycemia), muscle weakness, and poor growth. The disease primarily affects the liver and muscles, as these tissues rely heavily on glycogen for energy supply.
GSD III is classified into two types, type IIIa and type IIIb, based on the specific genetic mutations present. Type IIIa is the most common form and is characterized by the deficiency of GDE in both liver and muscles, resulting in more severe symptoms. Type IIIb, on the other hand, solely affects the liver, and individuals with this variant typically have milder symptoms.
Diagnosis of GSD III involves clinical evaluation, blood tests to measure glycogen levels and enzyme activity, and genetic testing to confirm the specific subtype. Treatment mainly aims to manage the symptoms and involves a well-balanced diet, frequent meals, and careful monitoring of blood glucose levels. In some cases, medication may be prescribed to control hypoglycemia.
Although GSD III is a lifelong condition, with careful management and ongoing monitoring, individuals affected by this disorder can lead healthy lives and enjoy good long-term outcomes.
