Glycogen storage disease

Introduction to glycogen accumulation Glycogen storage disease is a rare group of related autosomal recessive diseases in which patients cannot normally metabolize glycogen. Therefore, glycogen (a type of starch) accumulates in large amounts. The most serious glycogen storage disease is glycogen storage type II (Pangpo disease), usually occurring within 1 year of age. Glycogen accumulates in the liver, muscles, nerves and heart, making it unable to work properly. The tongue, heart, and liver grow up. The child is as weak and progressive as a baby, with difficulty breathing and swallowing. Ponper disease is incurable and most children die when they are 2 years old. Non-serious Pompe disease can be found in older children and adults, causing muscle weakness in the upper and lower limbs and deep respiratory dysfunction. Other types of glycogen storage patients have painful spasms and muscle weakness, usually appear after exercise, the symptoms vary. Avoiding exercise can make the symptoms subside. Muscle damage causes myosin to be released into the blood. Since myosin is excreted from the urine, urine tests can be used to diagnose glycogen storage disease. Myosin is harmful to the kidneys, restricting exercise can reduce myosin levels, drinking plenty of water, especially after exercise, can dilute myosin. When the level of myosin is high, diuretics can be used to prevent kidney damage. Liver transplantation is effective for glycogen storage disease but not for Pompe disease. basic knowledge The proportion of illness: 0.001% Susceptible people: no specific population Mode of infection: non-infectious Complications: liver fibrosis muscle atrophy ascites

Causes of glycogen accumulation

GSD is caused by the lack of enzymes involved in the metabolism of glycogen, which causes obstacles in the synthesis or decomposition of glycogen, causing the deposition of glycogen in tissues and causing disease. Due to the different types of enzyme defects, various types of glycogen metabolism diseases are caused. Types I, III, VI, and IX are mainly liver lesions, and types II, V, and VII are mainly muscle tissue damage.

Glycogen storage disease is a disorder of hereditary glycogen metabolism, and its incidence rate is 1/2 million. According to its enzyme deficiency (mostly catabolic defects), it can be divided into 12 types except for phosphorylase kinase deficiency. It is an autosomal recessive disorder. More patients than infants and young children died.

Cause:

Glycogen storage disease is autosomal recessive, while phosphorylase kinase deficiency is X-linked inheritance.

Pathogenesis:

The glycogen storage disease is a disorder of hereditary glycogen metabolism.

The synthesis and decomposition of glycogen in the body is carried out under the catalysis of a series of enzymes. When these enzymes are lacking, glycogen is difficult to be normally decomposed and synthesized, involving liver, kidney, heart, muscle and even various organs of the body. , hypoglycemia, muscle weakness, heart failure and so on.

Glycogen accumulation prevention

The glycogen storage disease is a disorder of hereditary glycogen metabolism, and there is no clear relevant prevention data. The incidence rate is 1/2 million. It can be divided into 12 types depending on the difference in its enzyme deficiency (mostly catabolic defects). Except for the lack of phosphorylase kinase, they are all autosomal recessive diseases. More patients than infants and young children died.

Treatment is mainly to delay the development of the disease, increase muscle strength, improve symptoms and improve respiratory suffering, prolong life, improve quality of life, and alleviate pain.

Glycogen accumulation complications Complications liver fibrosis muscle atrophy ascites

Liver fibrosis, muscle atrophy, abdominal varices, cirrhotic portal hypertension, ascites and esophageal varices.

Symptoms of glycogen accumulation syndrome Common symptoms Varicose rhythm arrhythmia Upper gastrointestinal bleeding Ascites Muscular atrophy Liver dysfunction Heart enlargement Heart failure Inability to hepatic enlargement

Glycogen storage disease mainly manifests as hepatomegaly and hypoglycemia, including type Ia (glucose-6-phosphatase deficiency) and more rare type Ib (G-6-P microsomal transferase deficiency), type III, type VI And phosphatase b kinase deficiency with X chromosome and autosomal recessive inheritance. Muscle-dysfunction glycogen storage disease mainly manifests as muscle atrophy, hypotonia, and dyskinesia, including V type, VII type, glycerol glycerol mutase deficiency and LDHM subunit deficiency, and other type II and type IV.

Examination of glycogen accumulation syndrome

Laboratory inspection:

1. Fasting blood glucose measurement.

2. Determination of total cholesterol and decanoyl glycerol.

3. Determination of blood lactate and uric acid.

4. Glucagon test.

5. Determination of liver function transaminase.

Other auxiliary examinations: bone X-ray examination, abdominal B-ultrasound, electrocardiogram, echocardiography, etc. should be selected according to the condition. Perform tissue or organ pathological biopsy if necessary.

Diagnosis and identification of glycogen accumulation

1.I type diagnosis basis

(1) Clinical manifestations: large liver, fasting hypoglycemia, short stature, obesity, etc.

(2) Blood biochemical examination: low fasting blood glucose, elevated blood triglyceride and cholesterol, elevated blood lactate and uric acid.

(3) Glucagon test: Intramuscular injection of glucagon, blood glucose measured every 15 minutes for 2 hours, normal humans after 10 to 20 minutes, fasting blood glucose can increase by 3 ~ 4mmol / L, the patient increased <0.1mmol / The blood glucose still does not rise within L2 hours, the lactic acid rises by 3-6mmol/L, and the existing lactic acidosis is aggravated, and the blood pH value is lowered.

(4) Liver biopsy: It is the basis for the diagnosis of this disease. The patient's liver glycogen often exceeds the normal value of 6%, the glucose-6-phosphatase activity is reduced or even absent, and there is a large amount of glycogen deposition in the nucleus.

(5) conversion of fructose or galactose to glucose test: rapid intravenous infusion of 25% solution prepared by fructose or galactose, blood taken every 10 minutes for 1 hour, blood glucose, lactose, fructose, galactose content, patients Blood glucose does not rise, and lactic acid rises significantly.

(6) X-ray examination of the bone: visible osteophyte delay and osteoporosis.

2. Type II diagnosis basis

(1) Symptoms and signs: The patient is underdeveloped, the heart is hypertrophied, and the muscles are slack.

(2) Increased creatine phosphatase and aldolase.

(3) Examination: Diagnosis depends on muscle and liver biopsy, electron microscopy shows deposition of glycogen particles, lack of 14-glucosidase, and skin biopsy fibroblast culture does not exist.

(4) Glycogen particles can be seen in amniotic fluid cells of early pregnancy.

3.Type III diagnosis basis

(1) Symptoms and signs: liver and muscle weakness.

(2) Glucagon test: After fasting intramuscular injection in the morning, the patient's blood glucose does not rise or rise very little; after 2 hours of eating, intramuscular injection, blood sugar can rise by 3 ~ 4mmol / L, blood lactate concentration unchanged.

(3) Liver or muscle biopsy: a purple reaction was determined with iodine, confirming the presence of a boundary dextrin. It can also be used for erythrocyte leukocyte iodine detection.

(4) Determination of erythrocyte and leukocyte starch 1,6-glucosidase activity

4. Type IV diagnosis basis

The patient had cirrhosis, hepatosplenomegaly, jaundice and ascites, and the liver tissue iodine test starch was purple-positive.

5.V type diagnosis basis

(1) Symptoms and signs: limited muscle activity, tendon, etc.

(2) beam arm exercise test: the patient's upper arm is tied to the blood pressure belt, and the air pressure is brought to the systolic blood pressure to block the blood flow, and then the patient is stretched and the finger is repeatedly exercised for 1 minute. The blood lactic acid is measured before and after the exercise. Lactic acid is increased after exercise, and blood lactic acid is not elevated in patients.

(3) Muscle biopsy: showing muscle glycogen accumulation and lack of muscle phosphorylase.

6.VI type diagnosis basis

(1) Symptoms and signs: Liver is large, and hypoglycemia may occur.

(2) Fasting or postprandial injection of glucagon: can not increase blood sugar.

(3) Liver biopsy: high glycogen content and low phosphorylase activity. This enzyme has low activity in leukocytes.

7. Type VII diagnosis basis

(1) Symptoms and signs: same as V type.

(2) Muscle biopsy: lack of phosphofructokinase, which is low in red blood cells.

8. Diagnostic basis for phosphatase b kinase deficiency

1 symptoms and signs such as liver enlargement; 2 determination of leukocyte or hepatocyte enzyme activity decreased.

9.X type diagnosis basis

1 liver enlargement; 2 positive glucagon test; 3 liver or muscle biopsy.

10.O type diagnosis basis

1 symptoms and signs; 2 glucagon test; 3 post-meal liver biopsy liver glycogen content lower than liver wet weight 0.5%; 4 red blood cell glycogen synthase activity detection.

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