When an extra chromosome is added to 21st autosomal chromosome, this leads to the development of which of the following?
When an extra chromosome is added to 21st autosomal chromosome, this leads to the development of which of the following?
Solution
Option 1 -> Sickle Cell Disease is caused by a point mutation in the hemoglobin gene, not by an extra chromosome.
Option 2 -> Klinefelter Syndrome results from an extra X chromosome (XXY) in males, not chromosome 21.
Option 3 -> Down's Syndrome is caused by trisomy 21, where there are three copies of chromosome 21 instead of two.
Option 4 -> Haemophilia is an X-linked recessive bleeding disorder, not caused by chromosomal addition.
Hence, Option 3: Down's Syndrome -> This condition occurs due to trisomy 21 (three copies of chromosome 21), typically resulting from nondisjunction during meiosis. It is characterized by intellectual disability, distinctive facial features, and increased risk of certain medical conditions. -> correct
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