I know what you're getting at, and it's a very difficult issue, but if you are advocating against screening out Down Syndrome then I disagree.
A question worth asking yourself is: If I had the power to give myself, or someone I love and want the best for, Down Syndrome, would I do so? Especially consider the case where the person is young enough not to remember life before the change.
I wouldn’t any more than I wouldn’t take away down from someone who was down. I’m not advocating about anything though, I am just stating the world is better with down people in it than without them. They are truly beautiful humans.
A close friend of mine worked in a "home" for people who had to fit all three of "adult," "violently disturbed," and "diminished mental capacity." They were not beautiful humans. While all types were present, the Down's crowd was just as nasty as the rest.
These folks get tucked away and the populace gets the high-functioning "nice" ones. Turns out that they're just as lousy as the rest of us.
A question worth asking yourself is: If I had the power to give myself, or someone I love and want the best for, Down Syndrome, would I do so? Especially consider the case where the person is young enough not to remember life before the change.