Glycogen storage disease type VII in children
Introduction
Introduction to VII type of glycogen storage disease in children Glycogen storage disease type VII (GSD-VII) is caused by defects in myosin fructokinase, which is rare and is mainly caused by muscle tissue damage. Glycogens storage disease (GSD) is a glycogen metabolism disorder caused by a class of congenital enzyme defects. The common biochemical feature of these diseases is abnormal glycogen storage. Most of the diseases are increased accumulation of glycogen in tissues such as liver, muscle and kidney. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: hemolytic anemia hyperuricemia
Cause
Pediatric glycogen storage disease type VII cause
(1) Causes of the disease
This type is caused by defects in myosin kinase.
(two) pathogenesis
Phosphofructokinase is a major enzyme in the glycolytic pathway that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-diphosphate, which is composed of three isozyme subunits (M-muscle, L- Liver, P-platelets; different isozymes are expressed in different tissues by their respective coding genes. The skeletal muscle contains the M subunit, and the coding gene is located at lcen-1q32. The mutation causes the enzyme in the muscle. Completely deficient and the enzyme activity in red blood cells is reduced by about 50% (hybrid enzymes containing M and L in the cells).
Prevention
Prevention of pediatric glycogen storage disease type VII
The prevention of glycogen storage disease type VII can refer to the prevention method of glycogen storage disease, which should include prevention of infection during pregnancy, avoiding old birth, close relatives, avoiding radiation, exposure to chemical substances, abnormal genetic material, etc., preventive eugenics measures :
1. Prohibit close relatives from getting married.
2. Premarital examination to discover genetic diseases or other diseases that should not be married.
3. The detection of the carrier is determined by group census, family survey and pedigree analysis, laboratory examination and other means to determine whether it is a genetic disease, and determine the genetic mode.
4. Genetic counseling.
5. Prenatal diagnosis of prenatal diagnosis or intrauterine diagnosis is an important measure of preventive eugenics.
The prenatal diagnostic techniques used are:
1 amniocytes culture and related biochemical examination (amniotic puncturing time is 16 to 20 weeks of pregnancy is appropriate);
2 pregnant women blood and amniotic fluid alpha fetoprotein determination;
3 ultrasound imaging (applicable in about 4 months of pregnancy);
4X line examination (after 5 months of pregnancy) is beneficial for the diagnosis of fetal skeletal deformities;
5 Determination of sex chromatin in villus cells (40 to 70 days of conception), predicting fetal gender to help diagnose X-linked genetic diseases;
6 application gene linkage analysis;
7 fetal mirror examination.
Through the application of the above technology, the birth of a fetus with severe genetic diseases and congenital malformations is prevented.
Complication
Pediatric glycogen storage disease type VII complications Complications hemolytic anemia hyperuricemia
Myosinuria can occur, accompanied by increased hemolytic serum bilirubin, hemolytic anemia, hyperuricemia, progressive myopathy.
Symptom
Pediatric glycogen storage disease type VII symptoms common symptoms hyperuricemia, weak proteinuria, nausea, muscle spasm, pain, weakness, myalgia
The clinical manifestations are mainly muscle weakness, characterized by decreased physical activity and muscle pain. It requires vigorous physical exercise, such as carrying heavy weights, running fast, going upstairs or climbing, etc., can cause muscle pain, tendon and Muscle stiffness; rest or slow down the speed of the activity can relieve the symptoms, the severity of the symptoms is proportional to the amount of exercise and the length of time, usually occurs in the limbs of myalgia, no hypoglycemic episodes.
1. Typical performance has the following five characteristics:
(1) This type of exercise usually has reduced exercise tolerance during childhood, and is more severe than V-type patients, may be accompanied by nausea, vomiting, muscle cramps and myosinuria often occur after strenuous exercise.
(2) accompanied by hemolysis characteristics, serum bilirubin increased, and the number of reticulocytes increased.
(3) Hyperuricemia is common and is more pronounced after exercise than in patients with GSD-V or III.
(4) Muscle biopsy can show abnormal glycogen accumulation in muscle fibers with similar branched starch, positive Schiff test, but not hydrolyzed by amylase.
(5) After eating a carbohydrate-rich diet, it is particularly intolerant to exercise because the muscle system of this type of child cannot use the glucose in the food, while the high concentration of glucose in the blood inhibits the decomposition of fat, resulting in muscle The fatty acids and ketone bodies in the cells are rapidly depleted.
2. Variant performance In addition to the above-mentioned typical children, there are two rare variants:
(1) Adult type: Infancy is the onset, the child's muscle tension is low, the limb muscle strength is poor, and the performance is progressive myopathy, often died around 4 years old.
(2) Adult type: characterized by chronic progressive muscle weakness, muscle painful spasm and myoglobinuria are rare.
Examine
Pediatric glycogen storage disease type VII examination
Laboratory tests showed that patients with elevated serum creatine kinase levels, even more after exercise; due to insufficient ATP supply of muscle energy during exercise, sputum nucleotide metabolism is so strong, resulting in blood ammonia, creatinine, hypoxanthine and uric acid The concentration also increased; hyperuricemia was common and was more pronounced after exercise than in patients with GSD-V or III.
After strenuous exercise, there may be myosinuria, accompanied by hemolysis characteristics, increased serum bilirubin, increased reticulocyte count, and hemolytic anemia.
Muscle biopsy can show abnormal glycogen accumulation in muscle fibers with similar branched starch. Schiff test is positive but not hydrolyzed by amylase. Enzymatic or histological examination of biopsy can provide a basis for diagnosis. Blood cells or fibroblasts can also be used. The M-type phosphofructokinase isoenzyme activity was examined.
X-ray, electrocardiogram, B-ultrasound and electromyography were routinely performed, showing progressive myopathy changes.
Diagnosis
Diagnosis and diagnosis of pediatric glycogen storage disease type VII
According to the medical history, physical signs and blood biochemical test results can make a clinical diagnosis, the phosphoryl fructose kinase activity of white blood cells and muscle tissue of sick children can be significantly reduced to help diagnose.
Identification with glycogen storage disease type V.
