What is the genetic basis that causes the symptoms of Down Syndrome?
What will be an ideal response?
Answer: Down syndrome is usually caused by an extra copy of chromosome 21. There are three types of chromosomal patterns that results in down syndrome. They are trisomy 21, mosaicism, and translocation.
Trisomy 21 means there is an extra copy of chromosome 21 in Every cell. This is the most common form of down syndrome.
Mosaicism is the least common type of down syndrome where there is an extra chromosome in some but not all of the cells.
About 5% of down syndrome occurs as a result of robertsonian translocation, robertsonian translocation results when the long arms of two acrocentric chromosome fuse at the centromere and the two short arms are lost.
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