metachromatic leukodystrophy
Introduction
Introduction to metachromatic leukodystrophy Metachromatic leukoencephalopathy (MLD), also known as heterochromatic white matter atrophy or heterochromatin leukoencephalopathy, was first reported by Alzheimer in 1910. An autosomal recessive hereditary disease caused by a deficiency of arylsulfatase-A. basic knowledge The proportion of illness: 0.005%-0.008% Susceptible people: no special people Mode of infection: non-infectious Complications: convulsions and convulsions
Cause
The cause of metachromatic leukodystrophy
(1) Causes of the disease
Heterochromococcal leukocystosis is an autosomal recessive inheritance. The mutated gene is located on chromosome 22 and is caused by the deficiency of aryl sulfatase-A.
(two) pathogenesis
Cerebroside sulfate is distributed in the cell membrane of nerve tissue myelin, renal tubular epithelial cells, etc. Under normal circumstances, arylsulfatase A catalyzes the hydrolysis of cerebroside sulfate, and decomposes galactose cerebroside into galactocerebroside And sulfuric acid, when this enzyme is deficient, causes the deposition of cerebroside sulfate in the body.
The main pathological changes were demyelination of the central nervous system and slight involvement of peripheral nerves. In pathological sections, when stained with toluene, red and yellow heterochromatic substances were deposited in nerve cells, glial cells and macrophages. Kidney tissue can also be affected at the same time.
Prevention
Metachromatic leukodystrophy prevention
Genetic counseling, prevention measures include avoidance of close relatives, carrier genetic testing and prenatal diagnosis and selective abortion to prevent the birth of children.
Complication
Metachromatic leukodystrophy complications Complications, convulsions and convulsions
As the disease progresses, the symptoms and signs that appear may be the manifestations of the disease, and can also be regarded as different types of complications of the disease.
Symptom
Symptoms of malnourinia, white matter, malnutrition, common symptoms, white matter, white matter, white matter, demyelinated white matter, less bedridden, unresponsiveness, slow decline, sputum, hyperreflexia, muscle tension, secondary infection, myoclonus
According to the onset age, it can be divided into late infant type (1 to 2 years old onset), juvenile type (4 to 15 years old onset) and adult type (onset after 16 years old), and the late infant type is the most common.
Typical patients can be divided into the following three phases:
Phase 1: Between 1 and 2 years old, the baby develops normally before the illness; after the onset, the child gradually loses exercise, the muscle tension decreases, the gait is paralyzed, the posture is difficult to maintain, and it is difficult to stand alone, sit, or even look up. Physical examination showed reduced muscle tone, decreased or disappeared tendon reflex, pale optic disc, negative pyramidal sign, normal or slower EEG, normal cerebrospinal fluid pressure, mild protein increase, and several weeks to several month.
No. 2: Sexual intelligence declines in sick children, language decreases to disappear, gradual reaction to the surrounding environment is reduced, screaming and bedridden, physical examination shows that the pupillary light is unresponsive, the optic disc is pale and atrophy, the face is expressionless, and the swallowing action is slow. Increased muscle tone in the limbs, limb extension, hyperreflexia, pathological pyramidal tract sign positive, but the trunk and neck muscle tension is normal or low, cerebrospinal fluid pressure, normal cells, protein increased, EEG diffuse slow Wave stove, this period of disease can last for one to several years.
No. 3: For advanced disease, the sick child rarely reacts to the outside world, often has seizures and myoclonic seizures, showing a special de-cortical tonic position, head recoil, strong tonic, muscular rigidity, and extremely difficult to lead out of quadriplegia. The pyramidal tract signs on both sides are positive, the pupils are scattered and the response to light is very poor, the eyeballs swim or have "doll" eye signs, severe obstacles of sucking and swallowing, and diffuse slow waves and scattered spikes appear on the EEG. The protein in cerebrospinal fluid is further increased to more than 1g/L. Most of the sick children have multiple infections, often suffering from 5 to 6 years old.
Juvenile and adult patients have late onset, slow progress, often with peripheral nerve sensation loss, and mental and behavioral abnormalities in the late stage.
Examine
Examination of metachromatic leukodystrophy
In urine, the activity of arylthioesterase A in blood leukocytes is reduced.
Peripheral nerve biopsy, heterochromic lipidoid particles were found in rectal mucosal biopsy.
Diagnosis
Diagnosis and diagnosis of metachromatic leukodystrophy
The clinical symptoms of this disease are no different from Krabbe's disease. The diagnosis is very difficult. Especially the diagnosis of adult patients is more difficult. The decrease of aryl thioesterase A activity in urine and blood leukocytes is the basis for the diagnosis of this disease. The patient's skin fibroblasts The culture of arylthioesterase A activity is more sensitive, peripheral nerve biopsy, rectal mucosal biopsy found heterochromatin lipid particles can confirm the disease.
Need to be differentiated from Pick disease, Alzheimer disease, etc.
