Eli5: Why does the one extra chromosome cause Down syndrome?

Question

Why does the addition of one extra chromosome cause Down syndrome, and how come that people of all backgrounds with Down syndrome have the same distinct features? How does the addition of one extra chromosome cause Down syndrome?

In: 27

Answer 1

Fun fact: that “trisomy” is a third chromosome, also called a triploid.

Strawberries used to be super tiny, but the big ones at the store we buy now have a chromosome that’s an octoploid. 1 extra chromosome causes Down’s syndrome. 6 extras make a strawberry bigger.