pediatric glycogen storage disease type Ⅳ
Introduction
Introduction to type IV glycogen storage disease in children Glycogenstoragedisease (GSD) is a glycogen metabolism disorder caused by a congenital enzyme deficiency. Glycogens storage disease type IV (also known as amylopectinosis, Andersen disease (Andersensdisease) ), caused by defects in starch 1,4-1,6-transglucosidase. Abnormal glycogen storage in the liver, kidney, spleen, muscle and nervous system of patients, especially in hepatocytes, the branch enzymes of liver, leukocytes and fibroblasts can be diagnosed and the intelligence is normal. There is no special treatment for this disease, only for symptomatic treatment. basic knowledge The proportion of illness: 0.005% Susceptible people: children Mode of infection: non-infectious Complications: cirrhosis, ascites, jaundice
Cause
Pediatric glycogen storage disease type IV cause
(1) Causes of the disease
This type is caused by a defect in the brancher enzyme. The gene encoding the branching enzyme (GBE1) is located at 3p12. According to the available data, the disease is an autosomal recessive disease, but the majority of the children are male. Therefore, the possibility of sexual chain inheritance cannot be excluded.
(two) pathogenesis
Branching enzyme, also known as -1,4-glucan: -1,4-glucan-6-glycosyl transferase, is glycogen An enzyme necessary for the synthesis pathway. The lack of this enzyme causes the linear growth of glycogen synthesis, and the branch point is sharply reduced. The molecular structure of glycogen is similar to the amylopectin of plants and is hardly soluble in water. This structurally abnormal glycogen molecule It has caused serious progressive damage of the liver. The mechanism is still unclear. About half of the patients may have damage to the heart muscle, skeletal muscle, central nervous system, and even a small number of patients with muscle and nervous system lesions. Therefore, It is speculated that the branching enzyme may have two isozymes belonging to different organs. The clinical manifestations of different patients depend on the type of enzyme deficiency, which may explain why this structurally abnormal glycogen molecule still has a small amount. The branch point (1,6 glycosidic bond) is present.
The liver presents with nodular sclerosis, irregular arrangement of hepatocytes, fibrous tissue hyperplasia, colorless or lightly stained inclusion bodies in the hepatocyte cytoplasm, and the boundary between the edge and the cytoplasm is obvious, and the inclusion body has a glass-like or reticular structure. The nucleus is often on the side, and electron microscopy and histochemical staining can show abnormal structure of glycogen.
Prevention
Pediatric glycogen storage disease type IV prevention
Detection of branch enzyme activity in cultured amniocytes or villous cells for prenatal diagnosis and termination of pregnancy if necessary.
Complication
Pediatric glycogen storage disease type IV complications Complications cirrhosis ascites jaundice
Weight does not increase, cirrhosis and portal hypertension can occur, ascites, abdominal varicose veins and esophageal varices, jaundice, etc., easily complicated by various infections, died of chronic liver failure.
Symptom
Pediatric glycogen storage disease type IV symptoms common symptoms weight loss portal hypertension abdominal wall venous varicose veins phlegm reflexes disappearance ascites jaundice gastrointestinal symptoms liver function failure muscle tension reduction
Children often have no symptoms within a few months after birth, but gradually appear liver, splenomegaly, abdominal distension, digestive tract symptoms and weight loss during 3 to 15 months, and may have low muscle tone, muscle Loss and atrophy, deep sputum reflexes and other neurological symptoms, as the disease progresses, cirrhosis and portal hypertension signs gradually become obvious, ascites, abdominal wall venous engorgement and esophageal varices, jaundice, etc., children easily complicated Infection, often dying from chronic liver failure within 3 to 4 years of age.
The clinical manifestations of branching enzyme defects are diverse. In recent years, a small number of adult cases confirmed by enzyme activity tests have been reported. These patients are mainly neurological and muscular disease symptoms. Peripheral nerve tissues and white blood cells of such patients are known. The activity of the branching enzymes in the plant decreased, and with the accumulation of data, there will be further understanding.
Examine
Pediatric glycogen storage disease type IV examination
The disease often has no hypoglycemia, oral glucose and fructose tolerance test is normal, glucagon or adrenaline test can make blood sugar rise slightly (0.8 ~ 1.3mmol / L), peak often occurs at 30min, serum cholesterol is light The degree of serum transaminase and alkaline phosphatase are significantly increased, serum protein and blood ammonia are often abnormal with liver function deterioration, and enzyme activity can be detected by liver, muscle tissue or red and white blood cells.
Conventional X-ray, B-ultrasound, electrocardiogram and electromyography, EEG examination, generally visible liver enlargement, spleen enlargement, ascites, cirrhosis, esophageal varices, electromyography, EEG Check for anomalies.
Diagnosis
Diagnosis and diagnosis of type IV glycogen storage disease in children
According to clinical features and laboratory tests confirmed.
Differential diagnosis
1. Identification with GSD-I: The pathological changes of liver tissue of this type are similar to those of GSD-I, but this type is rarely steatosis, and fibrosis is obvious. It does not involve the kidney clinically, and rarely causes severe hypoglycemia and heart failure. And arrhythmia is rare and can be identified.
2. Identification with von Gierke's disease: glucagon test can be used. Within 30 minutes of normal human injection of glucagon, blood glucose increased by at least 3.9mmol/L; while von Gierke's disease increased blood glucose <1.7mmol/L, both on fasting and after eating, which can be differentiated from GSD-III. If glucagon is given 2 hours after a meal, the blood glucose concentration will increase significantly. The adrenaline tolerance test is not superior to the glucagon tolerance test and may cause adverse side effects. Eating galactose or fructose to von Gierke patients does not result in an increase in blood sugar levels. This tolerance test should be avoided as much as possible, which can lead to severe acidosis.
