There is an interesting topic at Medpundit linking to an article describing situations where parents will, using Pre-implantation Genetic Diagnosis (PGD), intentionally select embryos "for the presence of a disability." Since I don't want to start an war Medpundit's comments section, I will elaborate here.
Medpundit correctly (I think) characterizes this is "still an egocentric mindset. Parenting as self-gratification." However, I disagree with this statement: "It's really no different than parents who use the procedure to avoid having a child with a disability."
With PGD, embryos are created in vitro and their DNA analyzed. If there are unwanted characteristics or genetic predispositions found (such as Huntington's Chorea, Tay Sach's disease, etc), that embryo is not implanted. I have two objections. First, who decided that a woman is pregnant only after implantation? The only difference between a newly-fertilized egg floating through the fallopian tube and one that is newly-implanted is merely a matter of real estate - location, location, location. The embyro's inherent properties remain exactly the same.
Therefore, using PGD to avoid having a child with a disability means that the offending embryo in question is not implanted. Since this will result in the death of that embryo, there is a gigantic difference between this and parents who use PGD to select a child with disabilities. While the latter calls into question those parents' suitability for raising children, the former is nothing less than infanticide.
As a former embryo myself, I think that just as children don't pick their parents, parents should not be allowed to pick their children.