Glycogen storage disease type V in children
Introduction
Introduction to V-type of glycogen storage disease in children Glycogens storage disease (GSD) is a glycogen metabolism disorder caused by a congenital enzyme deficiency. The glycogen storage disease type V is McArdle syndrome, also known as McArdle-Schmid-Pearson syndrome, CoriV type. Glycogen deposition disease, glycogen metabolism disease muscle type, muscle phosphorylase deficiency, etc., is autosomal recessive inheritance, muscle phosphorylase deficiency leads to inhibition of glycogen decomposition in muscle cells, ATP production is insufficient, so the main affected tissue is Striated muscle. basic knowledge The proportion of illness: 0.0003% Susceptible people: children Mode of infection: non-infectious Complications: acute renal failure
Cause
Pediatric glycogen storage disease type V etiology
(1) Causes of the disease
The disease is an autosomal recessive disorder. Due to the lack of muscle phosphorylase and normal liver phosphorylation, due to the lack of enzymes, normally synthesized glycogen cannot be provided as a fuel in the muscle, so the patient develops symptoms after strenuous exercise. .
(two) pathogenesis
The disease is caused by a mutation in the gene encoding the muscle phosphorylase of 11q13-qter, which is autosomal recessive; because the patient's liver phosphorylase is normal, the symptoms are limited to the muscular system, and the skeletal muscle lacks muscle phosphorylase. It causes the decomposition of glycogen in muscle cells to be blocked, and the production of ATP is insufficient. Therefore, the muscles can not use glycogen during exercise, and do not release lactic acid into the blood. The pathological feature is that a large number of structurally normal glycogens are accumulated in the muscle, and the muscle phosphorylase is deficient. .
Prevention
V-type prevention of pediatric glycogen storage disease
The disease must prevent acute renal failure secondary to myosin, avoid strenuous exercise, and rest in time.
Complication
V-type complications of pediatric glycogen storage disease Complications acute renal failure
Myosinuria may occur after strenuous exercise, and severe renal failure may occur in severe cases. Progressive dyspnea may occur in severe cases.
Symptom
Pediatric glycogen storage disease type V symptoms common symptoms dyspnea proteinuria weakness rhabdomyolysis fatigue muscle pain muscle spasm pain
Most children develop symptoms at school age or later. Some patients develop typical symptoms from late to adult stage. The clinical manifestations are mainly muscle weakness. They are characterized by decreased physical activity and muscle pain, carrying heavy objects and running fast. Upstairs or climbing, such as strenuous exercise requiring large physical activity, can cause muscle pain, tendon and muscle stiffness in the patient; rest or slow down the activity during sprint to relieve the symptoms, about half of the patients may appear temporarily after strenuous exercise Sexual red wine-like urine, which is due to rhabdomyolysis caused by myosinuria, severe cases can cause acute renal failure, the severity of symptoms is proportional to the amount of exercise and the length of time, generally occurs in In the limbs, the masseter muscle can also be painful after chewing. Although the symptoms can appear in childhood, some patients show typical symptoms in adulthood, but they have a history of tendon and fatigue, and the patient has muscle. Red proteinuria, but no hypoglycemic episodes.
A small number of early-onset children are severely ill, characterized by generalized muscle strength, low muscle tone and progressive dyspnea, and poor prognosis.
Examine
Pediatric glycogen storage disease type V 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; muscle biopsy revealed an increase in glycogen content and a decrease in muscle phosphorylase activity. After exercise, the pH of the muscle cells did not decrease, but the creatine phosphate content decreased significantly.
An ischemic exercise test is a rapid method for screening the disease, that is, using a sphygmomanometer to stretch the upper arm to maintain blood pressure between systolic and diastolic pressures, allowing the hand to repeatedly stretch and grip the movement; Before exercise, blood samples were taken at 1, 2, and 3 minutes after exercise to determine lactic acid and blood ammonia; blood lactic acid was not increased, and blood ammonia was significantly increased. The results of this test were deficient in phosphofructokinase, deficient in phosphoglycerase kinase, and phosphoglycerate. It is also abnormal in patients with enzyme deficiency and lactate dehydrogenase deficiency.
In a small number of patients, EMG may be characterized by inflammatory myopathy, and 31P magnetic resonance imaging can be used to assess muscle metabolism.
Diagnosis
Diagnostic identification of type G glycogen storage disease in children
1. A typical medical history is a diagnostic clue.
2. The hypoxia exercise test is positive. The blood pressure bandage is used to maintain the blood pressure in the systolic blood pressure. At the same time, the hand is stretched and the fist is exercised. Before the exercise, 1 part of the venous blood is taken at 1, 2, and 3 minutes after the start of exercise. The amount of lactic acid increased more than three times, and the patient did not respond, and the patient's side arm could be cramped.
3. Muscle biopsy shows an increase in glycogen and a decrease in muscle phosphorylase activity, which is responsive to injections of adrenaline or glucagon.
A small number of patients with electromyography may have inflammatory myopathy characteristics, which may lead to diagnostic difficulties, must be identified, ischemic exercise test in phosphofructokinase deficiency, phosphoglycerase kinase deficiency, phosphoglycerate mutase deficiency and lactic acid Patients with dehydrogenase deficiency are also abnormal and must be identified.
