According to CONGREGATION FOR THE DOCTRINE OF THE FAITH INSTRUCTION DIGNITAS PERSONAE ON CERTAIN BIOETHICAL QUESTIONS:
Preimplantation diagnosis is a form of prenatal diagnosis connected with techniques of artificial fertilization in which embryos formed in vitro undergo genetic diagnosis before being transferred into a woman’s womb. Such diagnosis is done in order to ensure that only embryos free from defects or having the desired sex or other particular qualities are transferred.
Unlike other forms of prenatal diagnosis, in which the diagnostic phase is clearly separated from any possible later elimination and which provide therefore a period in which a couple would be free to accept a child with medical problems, in this case, the diagnosis before implantation is immediately followed by the elimination of an embryo suspected of having genetic or chromosomal defects, or not having the sex desired, or having other qualities that are not wanted. Preimplantation diagnosis – connected as it is with artificial fertilization, which is itself always intrinsically illicit – is directed toward the qualitative selection and consequent destruction of embryos, which constitutes an act of abortion. Preimplantation diagnosis is therefore the expression of a eugenic mentality that “accepts selective abortion in order to prevent the birth of children affected by various types of anomalies. Such an attitude is shameful and utterly reprehensible, since it presumes to measure the value of a human life only within the parameters of ‘normality’ and physical well-being, thus opening the way to legitimizing infanticide and euthanasia as well”.
By treating the human embryo as mere “laboratory material”, the concept itself of human dignity is also subjected to alteration and discrimination. Dignity belongs equally to every single human being, irrespective of his parents’ desires, his social condition, educational formation or level of physical development. If at other times in history, while the concept and requirements of human dignity were accepted in general, discrimination was practiced on the basis of race, religion or social condition, today there is a no less serious and unjust form of discrimination which leads to the non-recognition of the ethical and legal status of human beings suffering from serious diseases or disabilities. It is forgotten that sick and disabled people are not some separate category of humanity; in fact, sickness and disability are part of the human condition and affect every individual, even when there is no direct experience of it. Such discrimination is immoral and must therefore be considered legally unacceptable, just as there is a duty to eliminate cultural, economic and social barriers which undermine the full recognition and protection of disabled or ill people.