OBJECTIVE LIFE SCIENCE
CELL BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Down Syndrome
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Turner’s Syndrome
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Klinefelter’s Syndrome
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Patau Syndrome
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Detailed explanation-1: -Down syndrome is also known as Trisomy 21, because the person has three copies of chromosome 21 instead of two.
Detailed explanation-2: -About 95 percent of the time, Down syndrome is caused by trisomy 21-the person has three copies of chromosome 21, instead of the usual two copies, in all cells. This is caused by abnormal cell division during the development of the sperm cell or the egg cell.
Detailed explanation-3: -Double aneuploidy (Down-Klinefelter syndrome) is rare, with an estimated incidence of 0.4-0.9 cases per 10, 000 male births and 11.7 cases per 10, 000 cases of trisomy 21 [7]. It is characterized by the presence of a third copy of chromosome 21 plus an extra X chromosome, resulting in 48 chromosomes (48, XXY, +21).
Detailed explanation-4: -Mainly there are three cytogenetic forms of Down syndrome: free trisomy 21, mosaic trisomy 21 and robertsonian translocation trisomy 21.