Trisomy 21 chromosomes are relatively rare. According to statistical data, such a case is observed 1 time for 600-800 births. At the same time, it is proved that the frequency of development of pathology grows with the increase in the age of the parturient woman.
What are the causes of the development of trisomy 21 chromosomes?
In order to understand what is meant by trisomy 21 chromosomes, it is necessary to know the causes and features of this pathology. Until now, there is no specific cause for the development of pathology. Many scientists come to the conclusion that the disease occurs as a result of numerous interactions between individual genes, which ultimately leads to the formation of trisomy. In this case, individual genes become more active. As a result of the observed imbalance, the further development of the organism, in particular the psychoemotional sphere, is disrupted. Of the 400 genes existing on 21 chromosomes, the majority function has not been established, which makes it difficult to identify the cause.
The only, perhaps, studied risk factor for the development of the disease is the age of the parents. So, during the research, it was found that in women of 25 years the probability of having a child with Down syndrome is 1/1250, by the age of 35 - 1/400, and by 45 years 1 of 30 born children has this pathology. At the same time, the probability of having a child with this syndrome in parents with the same pathology is 100%. However, if one child with Down's syndrome was born in healthy parents, the probability of having a second child with the same pathology is 1%.
How is the pathology diagnosed?
To exclude abnormality and the occurrence of trisomy 21 chromosomes in pregnant women, a so-called screening is carried out in the first trimester of each observed pregnancy. Simultaneously, also conducted a survey to exclude trisomy for 13 and 18 chromosomes. To do this, blood sampling is carried out in the interval of 10-13 weeks. Taken sample of the biomaterial is placed in a special apparatus, through which the presence of pathology is determined.
For the screening of trisomy 21, for the accurate result, the indicators of the norm, as well as indirect factors such as age, weight, number of fetuses, the presence or absence of bad habits, etc. are taken into account. Only after conducting a full study and calculating the risk of developing trisomy. planned consultation with a gynecologist.
However, only the results of this study can not serve as the main criteria for diagnosing Down's syndrome. The results of the screening are an indication for further examination of the fetus using invasive methods. If there is a high risk of developing pathology, chorion puncture is frequently performed, as well as amniocentesis with genetic examination of the collected material.
When and to whom is the screening given?
- the age of the pregnant woman is 35 years and over;
- presence in the anamnesis of serious complications, as well as unexplained pregnancies;
- chromosomal pathologies, as well as congenital malformations in previous pregnancies;
- presence in the family of pregnant hereditary diseases;
- various transferred infectious diseases, radiation radiation, as well as the reception in the early stages of pregnancy of drugs with teratogenic effect.