Question

what is the cytological basis of down's syndrome ? explain why babies born to young woman seldom/ never show this abnormality​

Answer 1

Explanation:

Half the chromosomes come from the egg (the mother) and half come from the sperm (the father). This XY chromosome pair includes the X chromosome from the egg and the Y chromosome from the sperm. In Down syndrome, there is an additional copy of chromosome 21, resulting in three copies instead of the normal two copies.

Risk factors include:

Advancing maternal age. A woman's chances of giving birth to a child with Down syndrome increase with age because older eggs have a greater risk of improper chromosome division. ...

Being carriers of the genetic translocation for Down syndrome. ...

Having had one child with Down syndrome.