## Did you know that...

...DNA chromosomes can be analysed even before a person is born? Such a method is called prenatal diagnostics and is used to examine the proper development of the foetus. One of the common cytogenetic methods is the direct collection of amniotic fluid, which also includes released foetal cells. From them, laboratory diagnosticians can isolate entire sets of chromosomes, which are after staining analysed under a microscope. In addition to the structure of individual chromosomes, diagnosticians also monitor their total number. If they detect a deviation from the standard number of 46 chromosomes, it means the presence of one of the severe diseases. The most well-known type of such a disease is Down's syndrome, which is caused by an extra chromosome 21. The condition where there are three chromosomes in the cells instead of two is called trisomy. Currently, the analysis of freely circulating DNA is relatively widespread as it is a non-invasive method. Subsequently, the presence of the most common trisomy is analysed using molecular biological methods (quantitative PCR). The disadvantage of such analysis is that it does not reveal structural changes of chromosomes. In addition to monitoring the proper development of the foetus, cytogenetic analysis of chromosomes are used to determine the cause of frequent miscarriages and infertility, as well as to determine the prognosis of cancer diseases.