mucopolysaccharidosis type Ⅱ
Introduction
Introduction to mucopolysaccharidosis type II Mucopolysaccharidosis type II is also known as Hunter syndrome, first described by Hunter (1917), and Wolff (1946) reported the first X-linked inheritance of the Hunter syndrome family. According to the clinical characteristics, biochemical abnormalities and genetic methods of this type, Mekusick (1965) classifies it as mucopolysaccharidosis type II, which is associated with recessive inheritance. It is only found in males, and the mother of the patient is a carrier but does not develop disease. basic knowledge The proportion of illness: the incidence rate is about 0.0005%-0.001% Susceptible people: male. Mode of infection: non-infectious Complications: chronic diarrhea pulmonary hypertension
Cause
Mucopolysaccharidosis type II etiology
(1) Causes of the disease
The cause of this disease is concomitant recessive inheritance. It is only found in males. The mother of the patient is a carrier but does not develop the disease.
(two) pathogenesis
The pathogenesis of this disease is that due to the lack of iduronic acid sulfate esterase in the patient, the degradation of acid mucopolysaccharide is hindered, and the enzyme gene is located in Xq27.3~q28, resulting in excessive deposition of mucopolysaccharide. Tissue cells, which are excreted in the urine, can eventually lead to dysfunction as the accumulation of mucopolysaccharide in the tissue cells increases.
Pathology: Histopathological changes are basically similar to type I, that is, there are excessive acid mucopolysaccharide deposition in lysosomes of various types of cells. Although there is no visible corneal opacity, microscopic examination can still be seen in corneal endothelial cells. A certain degree of mucopolysaccharide deposition, the mucopolysaccharides deposited in the internal organs are mainly heparan sulfate and dermatan sulfate.
Prevention
Mucopolysaccharidosis type II prevention
Glycogen accumulation disease is a group of children with disorders of hereditary glycogen metabolism. It is characterized by excessive accumulation of glycogen in the body tissue and difficulty in decomposition. It is rarely a metabolic disorder of glycogen, resulting in less glycogen storage in the body. The original cumulative disease is not a disease, but a group of diseases. There are 12 kinds of diseases currently identified. The clinical features are characterized by hypoglycemia. The organs involved are mainly liver, kidney and skeletal muscles. Chromosomal recessive inheritance, no gender differences, mostly in childhood, some patients to adults, the disease no longer develops, can maintain general health.
The patients are mainly due to the lack of certain enzymes that break down glycogen, such as glucose-6-phosphatase, -1,4 glucose chymase, phosphofructokinase, hepatic phosphorylation kinase and the like.
Parents of many patients marry close relatives, avoiding close relatives marriage is an important part of preventing this disease. Once glycogen accumulation is found, it is mainly to prevent and treat hypoglycemia, a small amount of meals, limit fat and total calories, limit physical activity, serum lactic acid The highest, should take sodium bicarbonate to prevent acidosis, corticosteroids, adrenaline, glucagon, etc. can help control hypoglycemia.
Complication
Mucopolysaccharidosis type II complications Complications chronic diarrhea pulmonary hypertension
Can be complicated by retinal degeneration and blindness, but also concurrent, progressive deafness, hepatosplenomegaly, chronic diarrhea, chronic respiratory infection, pulmonary hypertension, coronary infarction, heart enlargement.
Symptom
Mucopolysaccharidosis type II symptoms Common symptoms Deafness, diarrhea, hepatosplenomegaly, claw-toed joint, tonic lysosomal enzyme deficiency, heart enlargement, nodule systolic and diastolic murmur
The clinical symptoms of this type are similar to those of type I, but they are mild, the lesion progresses slowly, and it is normal at the time of birth. It develops backward from about 2 years old, and the bone and face are mild Hull syndrome, but it is lighter. Late, the progress is slower, there may be joint stiffness, claw-like hands, short, but no spine back bend, the skin is wrinkled or nodular thickening, especially the upper limbs and chest, sometimes symmetrical distribution, There are hairy, cornea is not turbid, but in the late stage with slit lamp examination can be seen mild turbidity, can be blind due to retinal degeneration, often progressive deafness, hepatosplenomegaly, often chronic diarrhea, breathing voice, often accompanied Chronic respiratory infections, pulmonary hypertension and coronary infarction are also common, often with heart enlargement accompanied by systolic and diastolic murmurs, severe insufficiency is more obvious.
This type can be divided into two subtypes according to the severity of symptoms: MPSII-A is heavy, mental insufficiency is heavier, more than 15 years old before death; MPSII-B is light, normal intelligence, long life, can survive to 40 ~ 50 years old or older.
Examine
Mucopolysaccharidosis type II examination
Excessive dermatan sulfate and heparan sulfate appear in the urine, which is the same as type I, but the content of dermatan sulfate is different, type II is 55%, and type I is 88%.
X-ray examination.
X-ray findings are similar to type I, but the changes are milder, the onset is later, the pygmy is usually mild, the second and fifth phalanx are short in the middle, the proximal metacarpal is not pointed, and the distal ulna and ulnar distal articular surface can be relatively inclined. Angled, mild stenosis of the wrist joint, adult often have secondary bone and joint changes.
Diagnosis
Type II diagnosis and identification of mucopolysaccharidosis
According to the special clinical manifestations of this type, combined with family history, pathological changes and related laboratory tests, the diagnosis can be confirmed.
It needs to be differentiated from type I. X-ray findings are similar to type I, but the changes are lighter and the onset is later. The gnomes are usually mild.
