What Is Mucopolysaccharidosis?

Mucopolysaccharidosis is a disease that occurs due to mutations in the hydrolyzing enzymes that degrade mucopolysaccharides in the lysosomes of human cells, resulting in loss of activity. Mucopolysaccharides cannot be degraded and metabolized, and eventually accumulate in the body. The disease is a very important type of lysosomal storage disease, which can be divided into 7 types such as , , , , , , and , among which is divided into A, B, C, and D. The four subtypes, type IV, are divided into IVA and IVB subtypes. Although the pathogenic genes and clinical manifestations of each type are different, they are collectively referred to as mucopolysaccharidosis because the substrates stored are all mucopolysaccharides.

Basic Information

nickname: Mucopolysaccharidosis, Mucopolysaccharidosis, Mucopolysaccharidosis, Mucopolysaccharidosis
English name: mucopolysaccharidosis

Visiting department: Endocrinology
Common symptoms: Rough face, cloudy cornea, stiff joints, short stature, enlarged liver and spleen, mental retardation, heart valve disease, ear, nose, and throat disease

Causes of Mucopolysaccharidosis

Except for type II, mucopolysaccharidosis is an autosomal recessive disease, which is caused by a congenital defect in lysosomal acid hydrolase. It is characterized by excessive oligosaccharide accumulation and excretion.

Clinical manifestations of mucopolysaccharidosis

Classic patients, taking type as an example:

Rough face

Large head, boat-shaped head, protruding forehead, thick eyebrows, protruding eyes, swollen eyelids, low flat bridge of nose, and nostril upturn. The lips are large and thick; the tongue is large and protrudes out of the mouth. Gingival hyperplasia, teeth are small and widely spaced. The skin is thick, the hair is thick, the hair is thick and rough, and the hairline is low.

Corneal opacity

As the disease progresses, corneal opacities become increasingly severe and can cause blindness.

3. Joint stiffness

Involvement of large joints, such as the elbow, shoulder and knee joints, restricts the mobility of these joints; the involvement of the hand joints, showing the characteristics of "claw-shaped hands".

4. Short stature

The patient had a short neck and kyphosis, and her growth was almost stopped at the age of 2-3 years.

5. Liver and spleen enlargement

Abdominal swelling and high abdominal pressure cause umbilical hernias and inguinal hernias, which are still prone to recurrence after surgical repair.

6. mental retardation

Patients may be mentally retarded at about one year of age. The best intellectual level is only 2 to 4 years old, and severe mental retardation.

7. Heart valve disease

In most patients, the heart is affected in the later stages of the disease and manifests as valvular disease, which can lead to congestive heart failure.

8. Otolaryngology

Chronic recurrent rhinitis, coarse breathing, snoring sleep, chronic obstructive apnea, thick voices, and chronic hearing loss are common in severe patients.

The symptoms of type II patients are milder than those of type I. This type is mainly male and the cornea is not cloudy. Type III patients have mental retardation as their main clinical manifestation; type IV patients have loose wrists. The thorax protrudes forward, similar to chicken breasts; type VI patients have normal intelligence and obvious corneal opacities; the clinical manifestations of patients with type can be very different, with severe manifestations of fetal edema, and light patients may only have short stature.

Mucopolysaccharidosis

1. Urine mucopolysaccharide quantification and electrophoresis

It is best to use morning urine for specimens. It can be found that the amount of mucopolysaccharides increases. Each type should have different types of mucopolysaccharides. For example, dermatan sulfate and heparin sulfate bands were found in type and type . Heparin sulfate was found in type patients. Banding. Type patients found bands of keratan sulfate. Urinary mucopolysaccharide electrophoresis of patients with type III and type IV is prone to false negatives.

2.X-ray film

An orthotopic chest radiograph shows ribs that look like streamers; a lateral spine radiograph shows that the thoracolumbar vertebrae are dysplastic with bird's beak-like protrusions; the left-hand orthotopic radiograph shows that the proximal metacarpals are pointed and each phalanx looks like a bullet "kind.

3. Head CT or MRI

It can be found that the ventricular enlargement caused by high-pressure traffic hydrocephalus.

4. Determination of lysosomal enzyme activity in peripheral blood

Specimen can be selected from peripheral blood leukocytes, skin fibroblasts and plasma. The enzyme activity was significantly reduced in patients with mucopolysaccharidosis type .

5. Mutation detection of lysosomal enzyme-related genes

With current technology, the vast majority of patients should detect mutations.

Diagnosis of Mucopolysaccharidosis

According to the special clinical manifestations of this disease, the diagnosis can be confirmed by combining the family history, X-ray examination and related laboratory examinations.

Mucopolysaccharidosis Treatment

There is no good method so far, and symptomatic treatment is often adopted, but the effect is not satisfactory. Enzyme replacement and gene therapy are being studied.