See
news.bbc.co.uk/1/hi/health/7287508.stm
I think the parents should have the right to refuse genetic testing of their embroyos, but I think its wrong to DILIBERATELY choose to have a deaf embryo. If an untested embryo happened to be deaf I would not have any issues.
Being profoundly deaf is not the end of the world, but it is an inconvience. I don't understand why the couple feel that its impossible for a hearing child with two deaf parents to learn BSL and share deaf culture.