A Glance At Down Syndrome
Down syndrome, an illness caused mainly because of an abnormality in the genes, occurs due to an inaccurate process of cell partition. The actual nu...
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 condition causes cognitive and physical impairments in the child. Such developmental disabilities can also be detected earlier, even when the baby has not been born yet, with the help of ultrasound and other screenings.
Most of the time, the age of the mother at which she gives birth to the baby is the leading cause of Down syndrome. It can be further sub-divided into three types:
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 type of Down syndrome is known as mosaicism. This is common in around 1-2% of people who have this illness. It occurs due to a fault in the separation of the 21st chromosome and happens after fertilization has taken place, resulting in a few cells of the body that have 46 chromosomes and some with 47 chromosomes. Similarly, the cells that have 47 chromosomes again have one extra 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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