Preimplantation genetics: a case for prospective action

Ethical Challenges of Germline Genetic Enhancement

The new reproductive technologies have opened the door to different processes of germline genetic enhancement by which the characteristics of an individual according to the interests of the agents involved could be selected during its gestation. Although the initiative is apparently oriented towards developing individuals that would excel in society, critical voices raise the concerns about that this approach would generate and need for a reflection on the ethical, social and legal implications of these techniques and their implementation in society. We reviewed the literature about these issues throughout their historical records to date, focusing on the moral arguments and non-clinical aspects that affect the legal and social environment. We have observed various trends of thought with divergent positions (proactive, preventive, and regulatory) as well as a large number of articles that try to reconcile the different approaches. This review illustrates a series of concepts from the ethics and philosophy fields which are frequently used in studies that evaluate the ethical implications of germline genetic enhancement, such as dignity, benefit, autonomy, and identity. In addition, amongst the many unresolved controversies surrounding genetic enhancement, we identify procreative beneficence, genetic disassociation, gender selection, the value of disability, embryo chimerization, and the psychosocial inequality of potentially enhanced individuals as crucial. We also develop possible scenarios for future debate. We consider especially important the definition and specification of three aspects which are essential for the deployment of new reproductive technologies: the moral status of the embryo undergoing enhancement, the legal status of the enhanced individual, and the responsibility of the agents executing the enhancement. Finally, we propose the precautionary principle as a means to navigate ethical uncertainties.

Using preimplantation genetic diagnosis to create a stem cell donor: issues, guidelines & limits

Successful preimplantation genetic diagnosis (PGD) to avoid creating a child affected by a genetically-based disorder was reported in 1989. Since then PGD has been used to biopsy and analyze embryos created through in viuo fertilization (IVF) to avoid transferring to the mother’s uterus an embryo affected by a mutation or chromosomal abnormality associated with serious illness. PGD to avoid serious and early-onset illness in the child-to-be is widely accepted. PGD prevents gestation of an affected embryo and reduces the chance that the parents will be faced with a difficult decision of whether to terminate the pregnancy. More controversial have been PGD to select the sex of the child-to-be for “family balancing” (rather than to avoid a sex-linked disorder), PGD for mere susceptibility to disease and for late-onset disorders such as Alzheimer diseas, and most controversially, PGD to create a donor child who is Human Leukocyte Antigen (HLA-matched with a preexisting sibling in need of stem cell transplant.

The expression of genes in human preimplantation embryos

The study of gene expression in human preimplantation embryos is establishing itself as a necessary dimension of developmental biology and medical genetics. Transcripts identified in human preimplantation embryos include housekeeping genes, transcription and growth factor genes, sex-determining genes, tissue-specific genes and novel genes, as well as genes of unknown function. Strategies are being developed which will eventually permit the most sophisticated gene expression studies on single human embryos of co-ordinated transcription and translational regulation. There is both a need for international co-operation for the systematic construction of expression maps and a need to establish databases of expression patterns during different stages of human development. Understanding how genes are regulated in humans is essential for understanding both normal development and disease. Until recently, studies of gene expression and regulation during embryogenesis were almost exclusively limited to prokaryotes and to eukaryotes other than man. The introduction of artificial reproductive technologies in conjunction with the development of recombinant molecular technologies applicable to single cells has made possible the study of human development at its earliest stages (Pergament and Bonnicksen, 1994). Although there are still enormous technical challenges, robust strategies have been, and continue to be, developed for connecting DNA sequence to such endophenotypes as timing and level of genes expression at the single cell level. Questions currently being asked in human developmental genetic studies concern the pronucleus, the zygote and the preimplantation embryo: what genes are expressed? When are they expressed? What functions do they perform and how, in sequence or in combination? And, what elements control and regulate their expression? This review provides an overview of current knowledge about the expression of different embryonic genes during early human development and discusses future prospects, which includes a need for international co-operation similar to the Human Genome Project.

Results of a survey of the legal status and attitudes towards preimplantation genetic diagnosis conducted in 13 different countries

Considerable differences in the regulatory oversight of preimplantation genetic diagnostic (PGD) services exist among countries, ranging from total bans on any embryo manipulation to the almost complete absence of any regulations or authority. A survey of centres offering PGD services revealed common concerns about the creation of embryos for research, altering the pattern of normal embryo development and the potential for misuse in the clinical application of PGD.

Gene therapy. Is the future here yet?

Despite the overwhelming number of articles on gene therapy that have been published in the last few years, there is a paucity of trials that have successfully demonstrated the clinical usefulness of this modality. The enthusiasm characterizing some of the earlier studies has given way to a more realistic approach. The next step is to develop more efficient vectors for effective targeting and persistent gene expression.

Human fetal gene therapy: moral and ethical questions

This two-part paper discusses moral and ethical questions raised by future trials of human fetal gene therapy. The first part examines broad moral issues to explore whether fetal gene therapy is a morally praiseworthy goal. Ought it be done at all? These issues include (i) how the concept of fetal gene therapy originally arose as a goal envisioned at the beginning of prenatal diagnosis, (ii) preimplantation genetic diagnosis as a better preconceptual alternative for parents at higher genetic risk, (iii) alternatives to genetic abortions, (iv) the social and economic priority of fetal gene therapy, and (v) whether fetal gene therapy is a "slippery slope" that will end in germ-line gene therapy. This part concludes that far more reasons exist to commend fetal gene therapy than to reject it, given its limits and modest social and economic priority. The second part responds to specific ethical questions that must be raised about any protocol for human gene therapy. These questions and issues are adapted to the prenatal situation: (i) how the previable fetus becomes a "patient," (ii) concern for clinical benefit and minimizing risks to the fetus and pregnant woman, (iii) concern for the voluntary and informed participation of the pregnant woman, the father, and for protection of their privacy, (iv) concern for fair selection of subjects, (v) considerations of harm to germ line cells, and (vi) the role of public oversight of fetal gene therapy. The article concludes by recommending a continuation of the consolidated Recombinant Advisory Committee (RAC) for the near future.