Post by masders on Feb 15, 2024 9:31:38 GMT
Down syndrome is one of the oldest known diseases in human history. It is a chromozonal disease – disorder at the level of chromosomes. In 2000, a genetic code of chromosome 21 was mapped and 29 genes were discovered on this chromosome which are the cause of this disease itself. Regarding the fact that Down syndrome appears, read the interview with Dr. Marinela Vasilevska, cytogeneticist at the "Acibadem Sistina" clinical hospital. Background In 1866 Dr. John Langdon Down, who worked with mentally disordered people, noticed that some of his patients were so similar that it was easy to assume that they were children of the same parents. In his general description he noted that these people had a broad and depressed face, thick tongue, small nose and mental retardation.
Later, this chromosomal genetic disorder was Moldova Email List called Down syndrome. How does Down syndrome occur? Human cells divide in two ways. The first has to do with the thick cell - mitosis, where in one cell there are two cells with the same number and type of chromosomes as the mother cell. The other type of cell division – meiosis is the cellular process that halves the number of chromosomes and causes the formation of gametes. So normal egg cells and sperm have 23 chromosomes and not 46 chromosomes. Down syndrome occurs as a result of incorrect cell division. During meiosis the chromosomal pairs must be separated and directed to the different sexes of the cell (male-female) which then divides, and this event is called "division". Sometimes it happens that a pair does not separate and goes to one gender of the cell.
This means that in the end this cell will have 24 chromosomes, while the other cell will have 22 chromosomes, this is a "non-division" process. The cause of the cell not dividing is not known, but ultimately it is related to the age of the mother. If a sperm or egg cell with an abnormal number of chromosomes joins a normal gamete, the fertilized egg cell will have an abnormal number of chromosomes. 95% of the cases of Down's syndrome have to do with the non-separation of the pair of chromosomes 21, therefore we have triplication of this chromosome, a mutation that causes Down's syndrome, which in scientific language is called Trisomy 21. The risk of Down syndrome increases with age It has been proven that the risk of pregnancy with Trisomy 21 or Down syndrome increases with the mother's age.
Later, this chromosomal genetic disorder was Moldova Email List called Down syndrome. How does Down syndrome occur? Human cells divide in two ways. The first has to do with the thick cell - mitosis, where in one cell there are two cells with the same number and type of chromosomes as the mother cell. The other type of cell division – meiosis is the cellular process that halves the number of chromosomes and causes the formation of gametes. So normal egg cells and sperm have 23 chromosomes and not 46 chromosomes. Down syndrome occurs as a result of incorrect cell division. During meiosis the chromosomal pairs must be separated and directed to the different sexes of the cell (male-female) which then divides, and this event is called "division". Sometimes it happens that a pair does not separate and goes to one gender of the cell.
This means that in the end this cell will have 24 chromosomes, while the other cell will have 22 chromosomes, this is a "non-division" process. The cause of the cell not dividing is not known, but ultimately it is related to the age of the mother. If a sperm or egg cell with an abnormal number of chromosomes joins a normal gamete, the fertilized egg cell will have an abnormal number of chromosomes. 95% of the cases of Down's syndrome have to do with the non-separation of the pair of chromosomes 21, therefore we have triplication of this chromosome, a mutation that causes Down's syndrome, which in scientific language is called Trisomy 21. The risk of Down syndrome increases with age It has been proven that the risk of pregnancy with Trisomy 21 or Down syndrome increases with the mother's age.