mucopolysaccharidosis type Ⅳ
Introduction
Introduction to mucopolysaccharid storage disease type IV Mucopolysaccharidosis type IV, also known as Morquio syndrome, osteochondral malnutrition, malformed cartilage dystrophy, atypical rickets, characterized by a marked shortened torso of the trunk, femoral head and hip The sputum showed progressive changes, the joints were enlarged, and the muscle ligaments were loose. The disease is autosomal recessive, both sexes can occur, males are slightly more than female. basic knowledge The proportion of the disease: the incidence of the disease is about 0.0004%-0.0008% Susceptible people: 4 to 5 years old Mode of infection: non-infectious Complications: pediatric hereditary spastic paraplegia
Cause
Mucopolysaccharidosis type IV etiology
(1) Causes of the disease
The cause of this disease is autosomal recessive inheritance, and the gene is located on chromosome 3.
(two) pathogenesis
The pathogenesis of this disease is; the chondroitin sulfate-N-acetylhexosamine sulfate sulfatase deficiency, the mucopolysaccharide excreted in the urine is mainly keratan sulfate, the gene is located on chromosome 3, in normal cells, this Enzymatic hydrolysis of N-acetylhexosamine-6-sulfate bond also plays a role in the hydrolysis of 4-sulfate bond. The specificity of this enzyme for 6-sulfate bond occurs in keratan sulfate and chondroitin-6-sulfate. Therefore, when the enzyme is deficient, the two mucopolysaccharide components are deposited on the tissue cells and cause cell dysfunction.
Pathology: The structure of bone and cartilage under microscope is obviously changed, the chondrocytes are swollen, contain a lot of acidic mucopolysaccharides, and there is focal necrosis of cartilage. The liver Kupffer cells have inclusion bodies, which are acidic in the brain cells. Polysaccharide deposition can cause degeneration and swelling.
Prevention
Mucopolysaccharidosis type IV 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 IV complications Complications Pediatric hereditary spastic paraplegia
Compression of the spinal cord can cause spastic paraplegia and respiratory muscle paralysis.
Symptom
Mucopolysaccharide storage disease type IV symptoms common symptoms hepatosplenomegaly joint ankylosis joint swelling flat foot knee varus eye wide wide corneal opacity
Generally, when 4 to 5 years old, it is difficult to walk and have spinal deformity. The short stature is mainly because the spine becomes short, and the limb is relatively long. When standing, the hand can reach the knee, the joint is swollen, and the wrist and knee are used. For the sake of a spherical shape, but no mucopolysaccharidosis I, type II joint stiffness, knee varus, flat feet, knee joints and hip joint deformities on both sides, forming a semi-squat posture, wrist, hand, ankle and toe joint Due to the relaxation of muscle ligament, it is hyperactive. These external deformities have special diagnostic significance. The intelligence is normal. The facial changes are nasal collapse, the distance between the two eyes is widened, the teeth are not neat, the hepatosplenomegaly is rare, and the age of onset of corneal opacity. The more mucopolysaccharid storage disease type I is late, usually obvious symptoms around 10 years old, aortic valve insufficiency occurs mostly in the age of 10 years, and its incidence increases with age, however, most patients die at 20 years old prior to.
Examine
Mucopolysaccharid storage disease type IV examination
Metachromatic mucopolysaccharide granules can be seen in neutrophils, but in the early stage, there is no such granule. Excessive keratin in the urine is specific for its change, sometimes as high as 45 mg/L, both for clinical and X-ray findings. Atypical, it is helpful for diagnosis.
X-ray examination.
Changes in the spine, pelvis, hand and wrist bones are common and characteristic.
Spine
The vertebral body is generally flattened, the transverse diameter and the anteroposterior diameter are increased, the thoracic vertebra is more obvious than the lumbar vertebrae, the intervertebral space is relatively widened, the surface of the vertebral body is irregular, and the anterior superior and inferior horns are often deficient, so that the vertebral body is wedge-shaped or the central anterior process is present. Tongue, these typical changes are common in the lower chest, upper waist, and the lower lumbar vertebrae tends to normal, the lumbar 1 or lumbar 2 often occurs in the posterior kyphosis, the vertebral body becomes smaller and shifts slightly backwards, much like the upper and lower vertebrae Extrusion, the lumbar lateral radiograph shows that the pedicle becomes longer, so that the anteroposterior diameter of the spinal canal increases, the ribs become flat and wide, and the spine ends become thinner, resembling a paddle.
2. Pelvis
The humeral wing is round and can have defects. The base is narrow and long, the acetabulum is shallow, the acetabular angle is increased, the upper edge is irregular, the femoral head is flattened, the callus is broken, the edges are irregular, and the femoral neck dry angle gradually After disappearing, the femoral head is completely absorbed, the femoral neck becomes thick and short, the hip valgus deformity is formed, the tibia is narrow, and the pelvis is narrowed at the level of the acetabulum to form a long and narrow pelvic cavity.
3. Hands and wrists
The change was similar to type I. The proximal metacarpal and distal phalanx were sharpened, the distal articular surface of the radius and ulna was relatively inclined, and the ossification center of the wrist was delayed and developed.
4. Long tube bone
It tends to become shorter, thicker, trabecular bone irregular, cortical thinning, dry sputum enlargement and irregularity, there may be a defect area, the center of the epiphysis appears sluggish, small and flat, often segmented, and integrated with the backbone Time delays, these changes are most obvious at the proximal end of the femur, joint gap widening or dislocation and deformity, such as hip valgus, knee valgus and shoulder joint sputum shallow.
Diagnosis
Diagnosis and identification of mucopolysaccharidosis type IV
According to clinical symptoms, X-ray findings and laboratory tests, the disease can be diagnosed.
Should pay attention to the identification of other types of mucopolysaccharidosis, achondroplasia, in addition, the disease should also be differentiated from congenital spine dysplasia, the latter short torso gnome, short neck, knee valgus, muscle weakness and Gait swing is similar to this disease and is easy to be confused. However, congenital spine dysplasia is autosomal dominant. The trunk is short when born, no corneal opacity, no abnormal mucopolysaccharide in the urine, and the vertebral body can be changed. Flat, but the intervertebral space does not widen, and there is a tendency to gradually narrow, the humerus changes lightly, the acetabular angle becomes smaller, the acetabular apex level, the hip varus deformity, and the proximal metacarpal without sharpening.
