In IVF procedures, preimplantation genetic diagnosis (PGD) is generally used to help prospective parents bear healthy children. Genetic testing performed on embryos can identify serious disabilities or diseases such as cystic fibrosis and Tay-Sachs disease, and these embryos are not selected for implantation in the woman's uterus.
The Science and Health section of today's NYT has this article about a new use for PGD: parents--who may not be infertile--using the procedure to select "for" a particular condition. A new article in the journal Fertility & Sterility presents the first actual data I've heard about on this issue. According to a study performed by the Genetics and Public Policy Center at Johns Hopkins, 3% of infertility clinics surveyed reported that they had intentionally used PGD to identify and implant embryos with a particular disability. (In press: Baruch S, Kaufman D, Hudson KL. Genetic testing of embryos: practices and perspectives of US IVF clinics. Fertil Steril 2006)
A lot has been written about whether PGD (and prenatal testing) to avoid the birth of people with disabilities is ethical--eliminating the disability by eliminating embryos. Adrienne Asch and David Wasserman offer the best (to my mind) argument for this view in a book chapter called "Where Is the Sin in Synecdoche?" (chapter 7 in Quality of Life and Human Difference: Genetic Testing, Health Care, and Disability).
In the present case, however, the closest parallel I can think of in the bioethics literature is the controversy about whether it is morally acceptable for Deaf parents, who see deafness as a necessary ticket to enter the Deaf culture, to decide against cochlear implants for their children. You can read more here, here, here, and here.
Lots of important questions here about disability, about what parents owe their children, about what's best for children, and about parental rights and how much say society should have over these questions.