21 March, World Down Syndrome Day

This 21 March, CymitQuimica would like to commemorate World Down Syndrome Day, dedicated to raising awareness and celebrating people with this syndrome. It is for this reason that we want to delve into understanding what Down syndrome is, its causes, and the current detection methods.

Typically, humans have 23 pairs of chromosomes, but in the case of individuals with Down syndrome, there is an extra copy of chromosome 21, and therefore, this condition is known as trisomy 21.

This extra chromosome results from an error in cell division, specifically during the stage of meiosis. Meiosis is the cell division process that occurs in reproductive cells (eggs and sperm) and is essential for sexual reproduction. During meiosis, parent cells divide to produce four daughter cells, each with half the number of chromosomes of the parent cell. However, as we have indicated, in the case of Down syndrome, an error can occur at one of the stages of this division, resulting in a reproductive cell with an extra copy of chromosome 21.

There are different ways this error can occur during meiosis:

• Nondisjunction:Occurs especially in the second stage of meiosis and is based on the incorrect separation of homologous chromosomes (a pair of chromosomes consisting of a paternal and a maternal chromosome that pair up within a cell). This can lead to one daughter cell receiving two copies of chromosome 21 and another none, resulting in a cell with trisomy 21 and another with monosomy 21.
• Translocation: In some cases, a portion of chromosome 21 attaches to another chromosome, generally chromosome 14. This can occur in a balanced way, which means there is no extra genetic material, but if unbalanced segregation occurs during meiosis, it can lead to a cell with trisomy 21.

Although these errors in meiosis are random, numerous studies and publications demonstrate that advanced maternal age(over 35 years) is the main risk factor associated with this syndrome. In fact, it has been documented that the risk for a 40-year-old mother is 16 times higher compared to a 25-year-old mother.

Thanks to advancements in detection methods over the past decades, this genetic condition can be detected before birth through prenatal screening tests. In the past, these tests were primarily based on invasive diagnostic techniques such as amniocentesis and chorionic villus sampling, which carried risks for the fetus and the mother.

With the progress of medical technology, non-invasive detection methods were developed, such as combined testing and the screening of fetal DNA in maternal blood, which provide accurate results, reducing the risks associated with invasive procedures.

These advancements have enabled the detection of Down syndrome, giving families informed choices, as well as access to adequate resources and support from the time of diagnosis.

As we commemorate World Down Syndrome Day, let us celebrate the diversity of all people with Down syndrome. At CymitQuimica, we advocate for inclusive communities where everyone, regardless of ability, is valued, respected, and has equal opportunities. Moreover, we support and continue to collaborate in the research of all genetic diseases and the mechanisms involved.