Glycogen Synthase Deficiency - A Rarely Diagnosed Condition

Introduction

Glycogen synthase deficiency is also known as glycogen storage disease type 0. Glucose is a major energy source required for the proper functioning of organs and systems in the body. Glucose gets stored up in the body as glycogen. Glycogen synthetase enzyme helps in the synthesis and degradation of glycogen. In this deficiency type, glycogen is not converted into glucose when required. It leads to a lack of sources of energy. Usually, glycogen is found in liver and muscle cells, which are storage units. Humans' main energy source is glucose, obtained from food. If glucose levels are low, it leads to fatigue and tiredness. The prevalence of occurrence of glycogen synthetase deficiency is unknown.

What Are the Types of Glycogen Synthase Deficiency?

1. Liver glycogen synthase deficiency.

2. Muscle glycogen synthase deficiency.

What Are the Causes of Glycogen Synthase Deficiency?

Glycogen synthase deficiency occurs when a gene mutation is present in the chromosome. The gene involved in mutation is GYS1, present in muscles, and GYS2, present in the liver. Both genes have the same function but function in different manners as needed by the organ. The GYS1 gene is involved in the process of formation of glycogen synthase. If any requirement, like rapid skeletal movements or any cardiac contraction, is there, this glycogen is converted to glucose and used. The GYS2 gene helps in the formation of glycogen synthase in the liver. It is used when the blood glucose levels are to be maintained by the conversion of glycogen into glucose. These mutations are transmitted from parents to their children. It occurs when both parents pass the same gene to their children. It usually appears in an autosomal recessive manner. It will be observed in childhood. It is usually asymptomatic or symptomatic in the infancy stages.

What Are the Symptoms of Glycogen Synthase Deficiency?

• Enlarged Liver: It occurs because the glycogen in the liver is not converted into glucose. This accumulated glycogen leads to an enlarged liver.

• Hypoglycemia: It occurs due to low blood glucose levels. When in need of energy, no glucose is obtained due to defects in conversion from glycogen to glucose.

• Lethargy: Due to unavailability of glucose for utilization leading to loss of energy.

• Slow growth.

• Tachycardia: Increase in heart rate.

• Hypotonia: Decreased muscle tone.

• Nausea and vomiting.

• Sweating.

• Pallor: Skin and mucous membrane turn lighter. It is assessed mainly in the eyes and nails.

• Ataxia: Loss of coordination of the body.

• Muscle pain.

• Obesity: Putting on being overweight.

• Low resistance to infections.

• Problems associated with bleeding and blood clotting.

• Seizures.

• Acidosis: Blood contains more acid.

• Hyperlipidemia: Cholesterol levels increased.

These symptoms appear in mild versions. It remains undiagnosed many times. When it is left untreated, it leads to serious health issues.

How to Diagnose?

A good healthcare provider will help it find out the disease condition. The doctor will ask for the main complaint, followed by symptoms, frequency of occurrence, and past health conditions. The doctor will ask for any family history because it is a genetically transmitted disease. This family history will sometimes hint to the doctor about the conditions. After that doctor does a clinical examination of the body to check for enlarged liver and weakened muscles. The patient is asked to undergo laboratory tests to confirm the disease state. Laboratory tests include:

• Blood Test:- Blood glucose levels are checked for hypoglycemia (reduced glucose level in blood). Another blood test involves liver, kidney, and muscle functioning.

• Ultrasound of the Abdomen:- It helps to identify any liver enlargement seen due to glycogen deposition.

• Biopsy of the Tissue:- It is a small procedure to obtain a liver or muscle tissue sample. It helps to evaluate the glycogen and enzymes present in the sample.

• Testing of Genes:- The patient's gene is tested for confirmation of the disease. The enzyme which has a problem with the gene is identified.

What Are the Treatment Options?

The treatment aims to maintain balanced blood sugar levels always throughout the day. It also must focus on glycogen not getting accumulated in the body. It helps to reduce the disease condition. It also helps to provide glucose when needed. It can be achieved by taking uncooked cornstarch or nutrition supplements. Easy digestion of corn starch is not possible, so it helps to maintain a normal blood glucose level for a greater time. It is better to give it at bedtime to prevent hypoglycemia in the morning.

In the morning section, taking small meals frequently (almost in a gap of two hours) will also help to maintain the blood sugar level without allowing the glycogen to accumulate. Simple carbohydrate intake should be limited. Carbohydrate solutions can be given when needing more glucose, but when an excess amount appears; it leads to accumulation. Exercise should be limited as during that time, glucose is needed, which can lead to hypoglycemia. Enzyme replacement therapy is also a choice of treatment to replace the missing or non-functioning enzyme. In the later stages, liver transplantation may be needed.

How Is the Prognosis?

Usually, a good prognosis is seen in patients with glycogen synthase deficiency. A good treatment plan and strictly adhering to it will bring good results. Dietary intake and hypoglycemic episodes, if prevented, can give a good result. A regular follow-up should be made with the healthcare provider. It helps to evaluate the condition of the patient. It provides insight into new treatment options.

What Are the Complications?

If no proper diagnosis and treatment are taken, or follow-ups are not done, it can lead to serious complications. If the patient goes undiagnosed with the disease with muscle glycogen storage disease, it may lead to cardiac arrest. Another issue is liver cirrhosis leading to liver failure.

What Are the Preventive Measures?

There are no ways to prevent this disease due to its nature of transmission. The main way to control these diseases is if any partners have glycogen synthase deficiency or suspect it before getting pregnant, they can visit a doctor. It helps in the early diagnosis of any disease if present. It helps to prevent further complications by early detection. Prevention is always better than cure. Early diagnosis, treatment, and follow-up are the only way to good and fast results.

Conclusion

Glycogen synthase deficiency is a rare disease in a body that lacks the enzyme glycogen synthase. This enzyme helps in the formation and disintegration of glycogen. Lack of this enzyme will lead to a lack of glucose when needed. In order to avoid this situation without panic, having small meals frequently helps to overcome this situation.