Slippery Subjective Significance

Is eugenics impending? The slippery, or maybe just slightly wet, slope leading there is discussed in a Slate.com article.
PGD stands for preimplantion genetic diagnosis. Simply put, it means that embryos for IVF(in-vitro fertilization) are screened for certain genes before they are implanted into the uterus. If an embryo has a specific gene (usually one associated with a type of cancer), the embryo is discarded or frozen. In other words, it's not used. The article goes on to try and define the "line". Where is the line drawn over what is screened for and what is not? Where is the line drawn for what is a significant risk of early- or late-onset disease? It further delves into treatability.
Regardless of most of these parameters, the significance of a certain disease and it's risk factors is dependent on the mother, or parents, of said embryo. Even though there may be "lines" drawn, the significance of any disease is subjective to the recipient. As Saletan writes, "if significance is subjective and anxiety is sufficient, won't some parents feel that severe asthma meets that standard?" One more step down the slope. Where does line finally get drawn?

As for Leather's assurance that PGD "can still only be used for a minority of
people if there is a clear history of cancer across generations of a family,"
why should anyone respect that line? Once genetic testing becomes cheap and
universal, why shouldn't anyone who finds out she has a cancer gene be able to
test her embryos for it?

This is why I can't bring myself to read much anymore, let alone drag myself off the couch. One article leads to another. Do I really want to know these things are going on in my world? Do I want to squander my time pondering the future in this world? I'd rather be watching "Mad About You". The problems never stretched far beyond the walls of Paul and Jamie's apartment.