the diagnosis of genetic pre-implantation (gpd) has extended its use and indications beyond the limits of genetic abnormalities detection. with the nash case, the first step to the so called, embryos' constructions has been taken, and for the first time, an embryo has been manipulated to benefit a third party alive. this work analyses the scientific and bio ethical aspects of this case. interpretation of the implications of kant's mandate transgression, that says that every rational being must be an end by itself and not a means to serve others. likewise, the warnings made by the philosopher jurgen habermas are exposed; the use of gpd as a positive eugenics technique. and last, other non medical indications of gpd and the bio-ethical dilemma are shown.