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The following is my response to this Mary Meets Dolly post on prediagnostic genetic testing for Downs Syndrome.
To add some facts arguing against your view on genetic testing for Downs syndrome:
In my home country, where the right to abortion has been established many, many years and where every women (public healthcare) over the age of 38 is offered genetic testing for trisomy 21, the number of children born with Downs has remained unchanged also after the introduction of genetic testing. Thus, your assumption that this testing leads to less children born with this syndrome may not hold true. Also, I do not think that most people believe that the world would be a better place without Downs. I think however, that most people understand that this is a severe disease and that life with Downs is a challenge for the family as a whole. As for the lessons of life, it is truly sad when someone says that we need the sick and disabled to learn these lessons. Such a statement demeans these patients by saying they function as tools for us to understand the less fortunate.
BIOpinionated 
the number of children born with Downs has remained unchanged also after the introduction of genetic testing
It’s worth noting that this is due to the very high rate of abortion of detected Down syndrome fetuses (close to 90% according to most surveys) being balanced by the increasing age of mothers. As the accuracy of screening improves I’d expect to see the rate of Down syndrome births plummet.
Daniel. Those are very good points. However, since this is offered to every women in this age group you are assuming that the increase in Downs syndrome births would otherwise be substantial. It would be interesting to see numbers from countries where testing is not as widespread. Another point I’d like to make is that there is a significant subset of mothers who decline the offered testing, and that subset of mothers may not change much over time. Both these factors may slow down the predicted decline in Downs syndrome births.