Spinal muscular atrophy (SMA), also known as spinal muscular atrophy, is a disease caused by the degeneration of motor neurons in the anterior horn of the spinal cord, causing muscle weakness and muscular atrophy.
According to the age of onset and the severity of muscle weakness, it is clinically divided into SMA-I, SMA-II, and SMA-III, i.e. infant type, intermediate type and juvenile type. The common feature is degeneration of cells in the anterior horn of the spinal cord, which is approaching
The bed showed progressive, symmetrical, widespread flaccid paralysis and muscular atrophy mainly at the proximal end of the limb. Mental development and sensation are normal. Differences between types are based on age of onset, speed of disease progression, and muscle weakness
Depending on the degree and duration of survival. So far, there is no specific and effective treatment for this disease. The main treatment measures are to prevent or treat various complications caused by severe muscle weakness, such as pneumonia, malnutrition, and skeletal deformity
shaped movement disorders and psychosocial problems.
Spinal muscular atrophy is an autosomal recessive inheritance and is caused by a homozygous deletion of exon 7 of the SMN gene.
nClassification:
1. Infantile-onset spinal muscular atrophy
Also known as SMA-I or Werdnig-Hoffmann disease. This type is the most serious among the 3 types. Some cases develop in utero, and fetal movement becomes weak. Half of them develop at birth or in the first few months after birth.
The disease develops, and almost all of them develop within 5 months. It is rare to survive for 1 year. These children have symptoms during the fetal period, with reduced fetal movement, and have obvious limb weakness after birth, feeding difficulties and breathing difficulties.
tCharacteristics:
(2) Muscle relaxation and extremely low tension When the child is in a recumbent position, the lower limbs are in a special position such as frog leg position, hip abduction, and knee flexion, and the tendon reflexes are reduced or disappeared.
(3) Muscle atrophy can affect the muscles of the limbs, neck, trunk and chest. Because infants have a lot of subcutaneous fat, muscle atrophy is not easy to detect.
(4) Intercostal muscle paralysis, mild cases may have obvious compensatory abdominal breathing. In severe cases, in addition to severe breathing difficulties, a depression on the sternum may be seen during inhalation, that is, thoracic contradictory breathing, and diaphragm movement is always normal.
(5) Motor cerebral nerve damage, the most common being hypolingual nerve involvement, presenting tongue muscle atrophy and tremor.
(6) The prognosis is poor, with an average life expectancy of 18 months, and most deaths occur within 2 years of age.
2. Spinal muscular atrophy intermediate
Also known as SMA-II, intermediate SMA, or chronic SMA, the onset is slightly later than Type I, the onset occurs more than within one year of age, and the progression is slow. The children grew and developed normally at 6 to 8 months old, and most cases showed near
Severe muscle weakness mainly at the end, and the lower limbs are heavier than the upper limbs. Many children with type II can sit alone, and a few can even stand or walk with the help of others, but cannot walk alone. Multiple micromyoclonus is the main cause
To express. The respiratory muscles were not involved, the swallowing muscles were not involved, and the sphincter function was normal. This type has a relatively benign course of disease, with a survival period of more than 4 years and can survive beyond puberty.
3. Juvenile spinal muscular atrophy
Also known as SMA-III, also known as Kugelberg-Welander disease, Wohlfart-Kugelberg-Welander syndrome or mild SMA, is the mildest manifestation of SMA. The disease occurs in advanced stages or in childhood
Symptoms appear in spring, starting with abnormal gait, weakness of the proximal lower limbs muscles, slowly progressing, gradually involving the distal lower limbs and upper limbs. Survive into adulthood. It appears as neuronal proximal muscular atrophy. It works
Children with SMA-III walking may have stumbling gait, lumbar protrusion, abdominal protrusion, and unnecessary tendon reflexes. The time spent walking independently is closely related to the age of onset of muscle weakness, and those who develop before the age of 2 will
You cannot walk around the age of 15, and those who develop the disease after 2 years of age can maintain the ability to walk until about 50 years of age.
Spinal muscular atrophy can be avoided throughthird-generation IVFtechnology, and PGD is a major category in third-generation IVF technology. The main functions of this technology can be summarized in one sentence:
Diagnose whether embryos carry pathogenic genes for certain monogenic diseases, and screen out healthy embryos that do not carry pathogenic genes. Compared with unscreened embryos, these embryos were transferred to the woman's daughter
After the palace, once babies are born alive, they will not suffer from these single genetic diseases, and the continuation of such genetic diseases in the family has since been eliminated.
