Glycogen storage disease type II
Introduction
Introduction to glycogen storage disease type II Glycogen storage disease is a disease caused by excessive metabolism of glycogen in tissues due to metabolic disorders of hereditary glycogen, which is different according to the enzyme deficiency causing glycogen metabolism disorder and the excessive deposition of glycogen in the body. Glycogen storage diseases are classified into 11 types. Glycogen storage disease type II (Pompe disease) is also known as acid maltase deficiency disease, the disease is autosomal recessive inheritance, can also be distributed. Clinically divided into infant, child and adult, glycogen storage disease type II (Pompe disease), caused by acid maltase deficiency (AMD), causing glycogen deposition in lysosomes, lysosomal proliferation, destruction Even releasing abnormal lysosomal enzymes and causing a series of damage to blood cell structure. The nervous system of glycogen storage disease type II is mainly dyskinesia, with muscle weakness such as muscle weakness, muscle atrophy and pseudohypertrophy. More common. basic knowledge The proportion of illness: 0.0003%-0.004% Susceptible people: no specific population Mode of infection: non-infectious complication:
Cause
Type 2 cause of glycogen storage disease
(1) Causes of the disease
The disease belongs to autosomal recessive inheritance and can also be sporadic. The gene encoding acid maltase in this disease is located in the long arm 23 region (17q23) of chromosome 17.
(two) pathogenesis
Glycogen storage disease type II (Pompe disease), caused by the lack of acid maltase deficiency (AMD).
Maltase includes both acidic and neutral maltase, which decomposes -1,4 glycosidic bonds and -1,6 glycosidic bonds to free glucose molecules. This disease is a lysosomal lack of acid maltase and cannot decompose glycogen. It is deposited in lysosomes, causing lysosome proliferation, destroying and even releasing abnormal lysosomal enzymes, resulting in a series of blood cell structure destruction, and the glycogen metabolism in vitro is normal.
Classification of glycogen storage diseases:
Defective type 1.0 urinary diphosphate glucose-glycotransferase, clinical manifestations of hepatomegaly, hypoglycemia, congenital muscle weakness, decreased muscle tone.
2. Type I glucose-6-phosphonate deficiency, clinical manifestations of hepatomegaly, hypoglycemia, ketotoxicity, acidosis.
3. Type II -1,4-glycosidase deficiency, heart enlargement, heart failure, giant tongue, muscle weakness.
4. Type III polysaccharide-1,6-glucosidase and/or fructose-1,41,4-transglucosidase deficiency, clinical manifestations of hepatomegaly, hypoglycemia, congenital muscle weakness, decreased muscle tone.
5. Type IV polysaccharide-1,41,6-transglucosidase deficiency, clinical manifestations of liver, splenomegaly, cirrhosis.
6. V-type muscle phosphorylase deficiency, clinical manifestations of muscle pain after exercise, weakness.
7. VI type liver phosphorylase deficiency, clinical manifestations of hepatomegaly, hypoglycemia.
8. Type VII phosphofructokinase deficiency, clinical manifestations of muscle pain after exercise, weakness.
9. VIII type hexose phosphate isomerase deficiency, clinical manifestations of muscle pain after exercise, weakness.
10. IXa type phosphorylase kinase deficiency, clinical manifestations of hepatomegaly, hypoglycemia.
11. IXb type phosphorylase kinase deficiency.
12. X-type phosphorylase kinase deficiency, clinical manifestations of muscle pain after exercise, weakness.
Prevention
Glycogen storage disease type II prevention
The method for predicting this disease is to measure the activity of acid maltose by intrauterine puncture and amniocentesis in 14 to 16 weeks of gestation. If it is reduced, the pregnancy should be stopped.
Difficulties in the treatment of genetic diseases, unsatisfactory results, prevention is more important, preventive measures include avoiding close relatives marriage, implementation of genetic counseling, carrier genetic testing and prenatal diagnosis and selective abortion to prevent the birth of children.
Complication
Glycogen storage disease type II complications Complication
Glycogen storage disease type II and type III can be complicated by respiratory infections, which is also one of the common causes of death.
Symptom
Glycogen storage disease type II symptoms common symptoms cyanosis limb weakness liver enlargement heart failure muscle atrophy arrhythmia dyspnea
Infant type
It usually develops after 1 month or 3 to 4 months of birth.
(1) The first symptom is cyanosis after eating, difficulty breathing, and respiratory distress.
(2) The muscles of the whole body are weak, flaccid paralysis, and the disease progresses rapidly, often dying within 1 year old.
(3) Check the visible giant tongue, the heart expands, a small number of sick children with enlarged liver, arrhythmia.
2. Child type
The main clinical manifestations of limb weakness are similar to limb-type muscular dystrophy. They often have difficulty breathing, cyanosis, enlarged heart, heart failure and gastrocnemius hypertrophy. The disease progresses slowly, often due to respiratory failure caused by lung infection, but Some patients can survive for more than 20 years.
3. Adult type
30 to 40 years old, slow and progressive limb muscle atrophy, weakness, proximal end is heavier, with trunk muscles, pelvic muscles are obvious, more than half of patients affect respiratory muscles, often misdiagnosed as polymyositis or muscle nutrition Adverse diseases have a good prognosis.
Examine
Glycogen storage disease type II examination
Blood biochemical examination
(1) Serum CPK is elevated, and liver function is in the normal range (adult type).
(2) The fasting blood glucose and glucose tolerance curves are normal.
(3) Adrenalin and glucagon tests were normal.
2. Blood smears see vacuolar lymphocytes.
Other inspection
1. Myoelectricity shows tonic potential activity, see muscle fibrillation potential, motor unit potential is normal or time limit is shortened, motor nerve conduction velocity is normal.
2. Muscle fibers of muscle biopsy showed scattered vacuoles of different sizes. PAS staining showed positive particles. Under electron microscope, glycogen was deposited on the muscle wall, and the muscle fibers in the myofibrils and phagocytic vacuoles were sparse and swollen.
Diagnosis
Type II diagnosis and identification of glycogen storage disease
The diagnosis of this disease depends on typical clinical symptoms, signs of the heart and muscles.
Infant type
Can be diagnosed according to the lack of acidic maltose and neutral maltose in the urine.
2. Child type
It can be diagnosed according to the decline of acid maltose in muscle, liver, heart and leukocytes.
3. Adult type
According to the muscle, the acid maltose in the liver is decreased or disappeared, and the neutral maltose is normal, or the muscle biopsy, more glycogen deposition is seen in the section, and the glycogen staining of the surrounding white blood cells is positive, and the diagnosis is confirmed.
Note the identification of other types of glycogen storage disease, polymyositis or muscular dystrophy, liver disease, metabolic syndrome (X syndrome).
