The Church of England is concerned that if Down's syndrome is completely eliminated, existing people with Down's syndrome might feel hurt that no more people will be like them.

This made me aware that the polio eradication campaign threatens a similar problem. If we complete the campaign, people with polio will eventually disappear. Good heavens! Should we stop the campaign?

There are people with congenital deafness that object to the idea of preventing or curing congenital deafness. Their culture, which they have developed to cope with deafness, would be lost of it nobody needed to cope with deafness any more.

If you want to be deaf, I think you should have that right. (We should not allow you the right to have a polio infection, because that would expose others to the risk of contagion.) But you are not entitled to impose deafness, or polio, or Down's syndrome, on anyone else.