Causes of Chromosomal Syndrome Abnormalities

Chromosomal abnormality is a very common disease in medicine. Its incidence rate is not particularly high. We humans have a total of 46 chromosomes. If one chromosome is missing or diseased, our body will suffer from various diseases and discomforts. The harm to newborns is quite large, and symptoms such as congenital mental retardation and developmental delay will appear. So what is the cause of chromosomal abnormality?

Chromosomes are the carriers of genes. Chromosome diseases are chromosomal abnormalities, which lead to abnormal gene expression and abnormal development of the body. The pathogenesis of chromosomal aberration is unclear. It may be caused by chromosome nondisjunction in the late stage of cell division or chromosome breakage and reconnection under the influence of various factors inside and outside the body.

1. Physical factors: the radiation environment in which humans live, including natural radiation and artificial radiation. Natural radiation includes cosmic radiation, earth radiation and radiation from radioactive substances in the human body. Artificial radiation includes radiation radiation and occupational exposure. Ionizing radiation is notable for causing chromosome nondisjunction. When human lymphocytes were irradiated or grown in irradiated serum, the frequency of trisomy in the experimental group was found to be higher than that in the control group, and it caused chromosomal aberrations such as dicentric chromosome ectopy and deletion.

2. Chemical factors: People are exposed to various chemical substances in daily life, some of which are natural products and some are artificially synthesized. They can enter the human body through diet, breathing or skin contact, and cause chromosomal abnormalities.

3. Biological factors: When cells in culture are treated with viruses, various types of chromosomal aberrations often occur, including breakage, fragmentation, and exchange.

4. Maternal age effect: When the fetus is 6-7 months old, all oogonia have developed into primary oocytes and entered the nuclear reticulum stage from the prophase of the first meiotic division. At this time, the chromosomes are loosened and stretched again, just like the previous nucleus, and remain so until before ovulation in puberty. This state may be related to the synthesis of yolk. By puberty, due to the cyclical stimulation of oocytes by FSH, only one completes the first polar body each month. The secondary oocyte is released from the ovary and enters the fallopian tube, where it undergoes the second meiotic division and reaches metaphase. If fertilized at this time, the egg will complete the second meiotic division, become a mature egg, and combine with the sperm to form a zygote, thus starting the development of a new individual until birth. As the mother ages, under the influence of many factors inside and outside the mother, the egg may also undergo many aging changes, affecting the relationship between the same pair of chromosomes during mature division and the behavior in the late stage of division, contributing to the non-disjunction between chromosomes.

5. Genetic factors: Chromosomal abnormalities can often show a familial tendency, which suggests that chromosomal abnormalities are related to genetics.

6. Autoimmune diseases: Autoimmune diseases seem to play a role in chromosome nondisjunction. For example, there is a close correlation between increased primary thyroid autoimmune antibodies and familial chromosomal abnormalities.

Clinical manifestations

Down syndrome is also known as trisomy 21 and congenital idiocy. This is the most common chromosomal disease in humans, with an incidence rate of 1/700 to 1/600 in newborns. It is the most common cause of mental retardation and accounts for 10% of cases of severe intellectual developmental disorders.

Seguin (1846) first reported the clinical manifestations of this disease, LangdoneDown (1866) gave a comprehensive description of the disease, and British scholars later called the disease Down syndrome. Lejeune et al. (1959) proved that the disease was caused by trisomy of chromosome 21 and advocated the use of the name trisomy 21 syndrome, which was recognized at the Denver Conference in 1970. In addition to Down syndrome, other chromosomal dysgenesis include Patau syndrome, trisomy 18, Criduchat syndrome, fragile X syndrome, ring chromosome syndrome, Klinefelter syndrome, Turner syndrome, Colpocephaly syndrome, Williams syndrome, Prader-Willi and Angelman syndrome, Rett syndrome, etc.

Treatment and prevention

Treatment: Chromosomal abnormalities are difficult to treat and the results are unsatisfactory. There is no effective medicine for the treatment of congenital intellectual disabilities caused by them. You can try traditional Chinese medicine treatment and rehabilitation training.

Prenatal examination: The prognosis of different types of chromosomal dysplasia is different, and most have a poor prognosis. Mental retardation and growth retardation are common characteristics of chromosomal diseases. Chromosomal dysplasia is difficult to treat and the treatment effect is unsatisfactory, so prevention is more important. Preventive measures include promoting genetic counseling, chromosome testing, prenatal diagnosis and selective abortion to prevent the birth of affected children. Pregnant women should have regular prenatal checkups so that if there is a problem with the fetus, it can at least be discovered early. Amniocentesis is one of the methods to detect whether the fetus has congenital chromosomal defects.

The above are some of the causes of chromosomal abnormalities. I believe everyone has a certain degree of understanding of this disease. In fact, we can prevent this type of disease. We should do a prenatal check-up after pregnancy and a premarital check-up before marriage to see if there are any hereditary diseases. We should do a good job of prevention and try to avoid tragedies.