Glycogen Storage Disorders

Glycogen storage diseases are rare genetic disorders affecting the body's ability to store or utilize Glycogen effectively. Symptoms may include recurrent blood sugar lowering, muscle weakness, and liver disease. Exactly which symptoms develop depends on the form of the disease, which is caused by one enzyme deficiency out of several. Although each type is very different, most can be treated well.

Glycogen storage disease 

Glycogen is the stored form of glucose and represents the body's essential energy reserve. Glucose, a simple sugar primarily acquired from dietary carbohydrates, is absorbed into the bloodstream after digestion. 

Since the body constantly needs glucose—especially for energy-intensive organs such as the brain—the extra glucose is stored as glycogen within the liver and muscles. Once blood glucose is low, various enzymes can break down glucose to create a consistent energy source.

In people with Glycogen Storage Disease (GSD), deficiency or absence of one of the enzymes involved in breaking down glycogen can disrupt this process. Glycogen can consequently accumulate abnormally within the liver or muscles, or it may not form correctly. This situation leads to complications, such as damage to the liver, muscle weakness, or other systemic effects

GSD is an inherited condition, implying that it is passed down from parents to the offspring. It is often found in infants or toddlers. However, some subtypes of GSD can occur during adulthood.

Types of Glycogen Storage Disorder

GSD Type	Enzyme Deficiency	Affected Area
Type Oa	Glycogen synthase-2 deficiency	Liver
Type la	Glucose-6-phosphatase deficiency	Liver
Type lb	Glucose-6-phosphate transporter deficiency	Liver
Type III	Glycogen debrancher deficiency	Liver
Type IV	Glycogen branching enzyme deficiency	Liver
Type VI	Liver phosphorylase deficiency	Liver
Type IXa	Phosphorylase kinase deficiency	Liver

GSD Type	Enzyme Deficiency	Affected Area
Type V	Muscle phosphorylase deficiency	skeletal muscles
Type VII)	Phosphofructokinase deficiency	skeletal muscles
Type X	Phosphoglycerate mutase deficiency	skeletal muscles
Type XI	Lactate dehydrogenase A deficiency	skeletal muscles
Type XII	Aldolase A deficiency	skeletal muscles
Type XIII	Beta-enolase deficiency	skeletal muscles
Type XIV	Phosphoglucomutase-1 deficiency	skeletal muscles

GSD Type	Enzyme Deficiency	Affected Area
Type IIa	Lysosomal acid maltase deficiency	Skeletal and cardiac muscles
Type IIb	Lysosome-associated membrane protein 2 deficiency	Skeletal and cardiac muscles
Type XV	Glycogenin-1 deficiency	Skeletal and cardiac muscles
Type 0b	Muscle glycogen synthase deficiency	Skeletal and cardiac muscles

Symptoms:

The symptoms of glycogen storage disease can vary based on the type and even from person to person with the same type. Some of the common symptoms include:

• Shaking or trembling.

• Sweating and chills.

• Dizziness.

• Weakness.

• Faster heart rate.

• Intense hunger (hyperphagia).

• Difficulty concentrating.

• Anxiousness 

• Pale skin.

• Seizures.

Other symptoms of GSD may include:

• Muscle cramps or muscle weakness

• Slowed growth

• Enlarged liver (hepatomegaly)

• Low muscle tone

• High cholesterol (hyperlipidemia)

Causes

A genetically inherited condition, glycogen storage disease passes from parents to children.

GSD occurs due to a mutation gene carried by both parents that affects a specific mode of glycogen storage or utilization. Most GSDs occur because both parents pass the same abnormal gene to their children. In most cases, parents never present with symptoms of the disease.

Since GSD is a rare disease, health professionals must have extensive knowledge of the issue, including symptoms, causes and diagnosis test, to discern what type of GSD it is.

And for that following are the tests they perform: 

• Fasting blood sugar test

• Liver function tests

• Urinalysis

• Abdominal ultrasound

• Genetic testing

• Basic metabolic panel

• Lipid panel

Understanding the basics of Glycogen Storage Disorders is just the starting point for students and professionals aiming to master the subject. That’s where DigiNerve steps in, offering expert guidance from seasoned professionals to enhance your learning experience.