New technologies in prenatal diagnostics

Did you know that March 21 is the International Day of a Person with Down Syndrome? 
The day was not chosen by chance, because Down syndrome is nothing more than a trisomy on chromosome 21. This is the most common genetic pathology. According to statistics, every 700th - 800th child on the planet is born with Down syndrome.

According to preliminary data from the Ministry of Healthcare of the Republic of Kazakhstan, in Kazakhstan for 3 years (2014-2016), there has been an increase in the morbidity of Down syndrome per 100,000 children under 14 years of age by 15%. The incidence rate in 2014 was 11.3 per 100 thousand children under 14 years old, in 2015 – 11.1 per 100 thousand children under 14 years old, in 2016 – 13.05 per 100 thousand children under 14 years old.

In total, according to preliminary data, in Kazakhstan, the number of registered patients with a diagnosis of Down Syndrome aged 0 to 18 years is 3,863 persons, of whom 707 are diagnosed for the first time in their lives.

There are several types of Down syndrome.

Down syndrome is usually caused by an error in cell division called "non-divergence". Non-divergence leads to the appearance of an embryo with three copies of chromosome 21 instead of the usual two. Before or at the time of conception, the pair of the 21st chromosome in the semen or egg cell is not separated. As the embryo develops, an additional chromosome is replicated in every cell of the body. This type of Down syndrome, which accounts for 95% of cases, is called trisomy 21.

Mosaicism (or "Mosaic Down Syndrome") is diagnosed when there is a mixture of two cell types, some of which contain the usual 46 chromosomes and some contain 47. These cells with 47 chromosomes contain an additional chromosome 21. Mosaicism is the least common form of Down syndrome and accounts for only about 1% of all cases of Down syndrome.

During translocation, which accounts for about 4% of Down syndrome cases, the total number of chromosomes in the cells remains 46; however, an additional full or partial copy of chromosome 21 is attached to another chromosome, usually chromosome 14. The presence of an additional complete or partial chromosome 21 causes changes characteristic of Down syndrome.

Regardless of the type of Down syndrome, all "special" people have an additional, critical part of chromosome 21 present in all or some of their cells. This additional genetic material alters the course of development and causes a number of characteristic features associated with Down syndrome. Children with Down syndrome have a characteristic appearance, an increased likelihood of a certain range of diseases (for example, congenital malformations of the cardiovascular system, acquired defects of the sensory system, etc.), a certain mental retardation, which causes slower mental development against the background of healthy individuals and worse social adaptation.

The cause of Down syndrome is still unknown. Maternal age was the only factor that was associated with an increased likelihood of having a child with Down syndrome as a result of non-disjunction or mosaicism. However, there is a higher birth rate of children with Down syndrome in women under the age of 35 (80%). There are no precise scientific studies that would indicate that Down syndrome is caused by environmental factors or parental actions before or during pregnancy. This diagnosis refers to congenital fetal pathologies recommended for termination of pregnancy.

In 2007, there was a breakthrough in medical genetics, as it became possible to isolate fragments of freely circulating fetal DNA in the peripheral blood of a pregnant woman. This discovery made it possible to determine the sex, Rh factor of the fetus and evaluate the karyotype of the fetus.

The OLYMP CDL branches since 2018 offers its patients a number of NIPT to determine the sex and Rh factor of the fetus, the presence of Down syndrome, Edwards, Patau, Di Giorgi, Angelman, etc. All this has become possible thanks to the constant improvement and development of the company. So currently, non-invasive tests are available in all cities of Kazakhstan and expectant mothers can find out not only the sex of the fetus, but also the state of the child's health without invasive analysis methods from the 10th week of pregnancy. The test is usually made between the 10th and 22nd weeks, and the results are received a week later. The technique is called "non-invasive" because traditional blood sampling from a pregnant woman's vein is sufficient for analysis, unlike amniocentesis, cordocentesis and chorionic villi biopsy. NIPT for Down syndrome may include screening for additional chromosomal abnormalities that are caused by deletion or duplication of sections of the chromosome. Take a NIPT today and enjoy your pregnancy.