Down syndrome, an illness caused mainly because of an abnormality in the genes, occurs due to an inaccurate process of cell partition. The actual number of chromosomes in all body cells is supposed to be 46. In this case, with the addition of another 21st chromosome, this illness of Down syndrome takes place.
This leads to a number of cognitive abnormalities and physical disabilities in the child that is born. These can also be identified earlier, before the birth of the baby through tests and screenings.
The factor that has the highest likelihood of leading to Down syndrome is that of maternal age. There are basically three types of Down syndrome:
Trisomy 21 is the most common type of Down syndrome. In this condition, every individual has 47 chromosomes instead of the normal 46. According to statistics, around 95% of people who have Down syndrome have this condition.
Trisomy 21 takes place before or just when conception occurs. As an error takes place during the cell division, each cell in the body has an extra copy of the 21st chromosome.
The second kind of Down syndrome is called mosaicism, occurring in approximately 1-2% of people with this problem. As this arises after fertilization has happened, it leads to a few cells with 46 chromosomes, while some having 47. The factor that leads to mosaicism taking place is a mistake in the partition of the 21st chromosome.
Lastly, translocation occurs in 3-4% of babies born with this condition. This happens because of the breakdown of one part of the 21st chromosome, which gets attached to the 14th chromosome. The reason why this type of Down syndrome may occur is attributed to the unusual genetic distribution of at least one parent of the child, who is suffering from it.
This leads to a number of cognitive abnormalities and physical disabilities in the child that is born. These can also be identified earlier, before the birth of the baby through tests and screenings.
The factor that has the highest likelihood of leading to Down syndrome is that of maternal age. There are basically three types of Down syndrome:
Trisomy 21 is the most common type of Down syndrome. In this condition, every individual has 47 chromosomes instead of the normal 46. According to statistics, around 95% of people who have Down syndrome have this condition.
Trisomy 21 takes place before or just when conception occurs. As an error takes place during the cell division, each cell in the body has an extra copy of the 21st chromosome.
The second kind of Down syndrome is called mosaicism, occurring in approximately 1-2% of people with this problem. As this arises after fertilization has happened, it leads to a few cells with 46 chromosomes, while some having 47. The factor that leads to mosaicism taking place is a mistake in the partition of the 21st chromosome.
Lastly, translocation occurs in 3-4% of babies born with this condition. This happens because of the breakdown of one part of the 21st chromosome, which gets attached to the 14th chromosome. The reason why this type of Down syndrome may occur is attributed to the unusual genetic distribution of at least one parent of the child, who is suffering from it.
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