Preimplantation Genetic Diagnosis - Essay Example

Ethical Review on Preimplantation Genetic Diagnosis (PGD) Introduction Preimplantation genetic diagnosis (PGD) allows couples undergoing in vitro fertilization (IVF) for infertility to screen their embryos for a host of genetic diseases and disorders. And it was first done in 1988. Preimplantation genetic diagnosis is a process that is used during an IVF cycle to identify specific embryos that carry abnormal genes. Selection of a particular sex is also being done using PGD. This is usually to avoid sex-specific diseases but it can also be done for family balancing. In general PGD is recommended for couples where one or both of the parents are a known carrier of a genetic disease (i.e. hemophilia or cystic fibrosis). The procedure of PGD involves the following steps. It is usually performed after a woman’s eggs have been harvested and fertilized by her partner’s sperm but before the fertilized eggs have been transferred back to her uterus. When the fertilized egg has multiplied to four and 10-cell development stage, one or two cells known as blastomeres are gently removed from each embryo. This is usually done using a microsurgery technique similar to that used in ICSI. The DNA from the removed blastomeres is then studied for any genetic diseases or disorders. If any are found to be having diseases or disorders, then those embryos are destroyed. Only those healthy embryos with no diseased genes will be transferred back to the mother. PGD has helped to diagnose numerous diseases and disorders classified as either chromosomal disorders, single gene defects or sex-linked disorders. The science of PGD has advanced so much that specific chromosomes are tested for specific disorders, for example Chromosome 13 is analysed for Breast and ovarian cancers, deafness, Wilson Disease; Chromosome 15 for Marfan Syndrome, Tay-Sachs Disease; Chromosome 16 for Polycystic kidney disease, Alpha thalassemia; Chromosome 17 for Charcot-Marie-Tooth Disease; Chromosome 18 for Niemann-Pick Disease, pancreatic cancer; Chromosome 21 for Downs Syndrome; Chromosome X for Duchenne muscular dystrophy, Turners Syndrome, Fragile X Syndrome; and Chromosome Y for Acute myeloidleukemia (Pregnancy-Info.net. 2005). The purpose of this paper is to explain current and likely future uses of PGD, and provide a complete review on the ethical issues on PGD. Ethical Concerns about PGD Preimplantation genetic diagnosis (PGD) is a common topic for debate as it is the technique by which early human embryos are genetically screened and then discarded or placed in the uterus. Reports that embryos are being screened for new indications such as susceptibility conditions, late-onset diseases, HLA matching for existing children, and gender, support the need for greater public attention. Today, the use of PGD is growing. However, only a small number of people using assisted reproduction (IVF) are likely to use PGD to screen embryos. Couples undergoing IVF in general go for PGD because IVF is a very expensive procedure and they would like to reduce the chances of any complications in future. Besides, PGD is least burdensome for a couple already going through IVF for infertility due to different reasons. A common couple with normal pregnancy, however, would only seek PGD if they were at special risk for genetic disease, and like to have a child without risking an affected pregnancy or later abortion. In either of the cases prenatal diagnosis would still be done to confirm that a fetus does not have the condition that the couple is seeking to avoid. Several new indications for PGD single gene mutational analysis have been reported. In recent years PGD is used to detect mutations for susceptibility to cancer and for late-onset disorders such as Alzheimer’s diseases. Additionally, parents with children requiring haematopoietic stem-cell transplants have also used PGD to ensure that their next child is free of disease and is a good tissue match for an existing child (Robertson, 2003). PGD was used entirely for medical purposes until recently. The ethical concerns on PGD started when Dr. Norbert Gleicher in 2001, requested the American Society of Reproductive Medicine (ASRM) to endorse the use of PGD for sex selection for “gender balancing”. Gleicher, who is a fertility specialist argued that PGD should be allowed for sex selection because it is comparatively a “more accurate” technology than pre-conceptive methods of sex selection, such as sperm sorting, which were deemed ethically permissible by the Society’s Ethics Committee (ASRM, 2001). However, the ASRM eventually denied Gleicher’s request, and upheld its 1999 policy which states: “The initiation of IVF with PGD solely for sex selection holds [even greater] risk of unwarranted gender bias, social harm, and the diversion of medical resources from genuine medical need. It therefore should be discouraged” (ASRM, 1999). The surfacing of new uses for PGD has made this procedure a frequent target of ethical commentary and speculation about a future of how PGH could be used for genetic selection and manipulation of offspring (Fukuyama, 2002; Kass, 2002; Stock, 2002). Using PGD for selecting specific sex might lead to demand for PGD in some cultural contexts. Where as other uses such as diagnosing for disorders and diseases may decrease in future as more and more sophisticated techniques are coming up. Finally, PGD is expected to be more and more sought by patients in narrow risk groups and to some extent for sex selection, but that demand will restrict to a small percentage of people using assisted reproductive and prenatal services. In general there are two main sets of ethical objections that make PGD controversial. The first set of objections arises from the need to create and then select embryos on chromosomal or genetic grounds, and discarding the embryos that are not selected. The second objection is the selection itself. The first objection starts when people who consider embryo or fetus to be a person, and they will object to creating and destroying embryos, and oppose most uses of PGD. On the other hand some others consider that preimplantation embryos are too rudimentary in development to have interests or rights of there own, however they deserve special respect as the first stage toward a new person (American Society of Reproductive Medicine, 1994). PGD is ethically good enough when done for good reasons, such as preventing offspring with serious genetic disease. Without a doubt PGD may prevent selective abortions for those diseases and there by prevent the depression in some people who undergo costly procedures such as IVF. A second set of objections arises from the fact of selection itself, for instance if PGD is used to selected specific characters in the child. Such practices are considered ethically and morally wrong in religious view. Ethical objections to selecting offspring traits raise two kinds of ethical concerns. The first one is deontological which is the ethical judgement that it is wrong to choose traits of offspring, no matter how well intentioned. Dr Leon Kass chairs the President’s Bioethics Council in the United States and they argue that human reproduction is a ‘gift’ and that any form of selection or manipulation turns the child into a ‘manufacture’ and thus impairs human flourishing (Kass, 2002). The second kind of concern arises from fears that increasing the frequency and scope of genetic screening of prospective children. Selecting embryos with desired genes affords parents an unprecedented level of control over the genetic make-up of their children. In fact such activity will lead us toward a eugenic world in which children are valued more for their genotype than for their inherent characteristics, eventually ushering in a world of ‘designer’ children in which genetic engineering of offspring becomes routine (Robertson, 2003). Eugenics is not a new phenomenon and it is the term used to indicate the genetic improvement of the human race by controlled selective breeding (Lynn, 2001). Disability rights activists who argue that the use of PGD to select against genetic conditions implies that those living with such conditions should never have been born have long recognized the eugenic nature of PGD. Similar arguments have been put forth in opposition to ever-expanding applications of prenatal screening. PGD has an even greater eugenic potential than prenatal screening, and may be used to select “the best” children. Other ethical concern on PGD is that it encourages a reductionist view of human health, where genes and genetics are ever more used to describe and differentiate health and illness, normality and abnormality, or better and worse personhood. Though genes are clearly important factors in the expression of certain diseases, environmental, social and institutional factors, as well as cultural attitudes towards medical conditions are equally important aspects. Hence it should be noted that “Technofix” solutions of disease avoidance should not replace efforts to develop disease treatments or address broader environmental and social factors of disease. In all these cases women who bare the child have to undergo various forms of discomforts. Increasing uses of PGD could eventually reduce women’s choices in childbearing. Growing diagnostic capability is broadening as a result all such diagnostic procedures are carried out which becomes a financial and also a physical burden. Women may feel more and more burdened by pressure to undergo this expensive, potentially risky, and maybe unnecessary procedure to avoid the birth of a child that does not fit these definitions. More generally, deep, social inequalities, together with the high cost of PGD mean that even potentially beneficial applications of PGD will be available only to the well-off in the society. Such a differentiation in access will only further exacerbate existing inequalities in the society. Besides, PGD is not a totally risk-free procedure. The damage caused to the early-stage embryo from removal of one of its cells and the potential long-term health effects to the child selected are still mysterious. In addition, PGD relies on IVF, a troublesome and risky procedure with a low success rate of around 25%. Hormonal treatments required to stimulate the woman’s ovaries to extract eggs have caused major, long-term health problems, including ovarian hyperstimulation syndrome which is a potentially life-threatening condition. In addition, the high rates of multiple births associated with IVF are a further source of risk to both the woman and the potential children. In two of the recent studies it is suggested that even in cases of singleton births, infants conceived by IVF have an increased risk of low birth weight (Schieve, et al. 2002) and twice the risk of major birth defects (Hansen, et al, 2002) than those conceived naturally. Above all, the genetic tests used in PGD are not 100% reliable and are subject to interpretation. The recent statement that potentially hundreds of pregnancies may have been unnecessarily terminated because of misinterpretation of prenatal tests for mutations associated with cystic fibrosis attests to the general complexity of genetic factors in disease occurrence as well as the need for vigilance in allowing testing without adequate standards and oversight. While PGD was originally proposed for use in avoiding the birth of children with severe, genetic conditions, recent applications of PGD go well beyond this use. A number of applications of PGD have emerged in the past few years that raise new ethical and moral concerns about PGD. These can be summarised as follows: Sex selection: Screening for sex is not new. In fact, some of the first applications of PGD were to screen for sex, only the intent was to avoid passing on a severe, sex-linked disease, such as hemophilia and Duchenne’s muscular dystrophy. However, in the past few years, some fertility clinics in the U.S. and Australia have begun offering PGD for sex selection for “gender balancing” (Simoncelli, 2003). Next, some fertility clinics have recently started to advertise PGD for selecting against breast cancer or prostate cancer, by selecting for boys or girls, respectively (Institute for Reproductive Medicine and Genetic Testing, 2002). Avoidance of late-onset diseases: A Chicago fertility in February, 2002, center provided PGD to a woman diagnosed as having a predisposing genetic mutation for early-onset Alzheimer’s disease, which strikes adults in their 30’s and 40’s. This case raises new questions of whether it is appropriate to provide PGD for prevention of an adult-onset disease and to a woman who may not be able to care for or even recognize her child in a few years (Towner and Loewy, 2002). There are several similar cases in other parts of the world. Tissue-typing to save the life of another child: “Tissue-typing” refers to selecting a tissue-match for another child with a disease and in need of a transplant. Starting in the late-1990’s, several cases of “tissue-typing” using PGD have emerged. The use of PGD for tissue-typing has occurred in both the United States and the United Kingdom. Susceptibility conditions: PGD has been used to avoid the birth of a child with a genetic mutation that has been associated with Li-Fraumeni syndrome, and may soon be extended for BRCA 1 and 2 susceptibility for breast cancer (Robertson, 2003). Generalized aneuploidy screening for IVF patients: In the past few years, PGD is being recommend to all couples undergoing IVF to select for embryos expected to have the highest developmental potential as a way of boosting success rates of IVF. However, this generalized, “aneuploidy screening” involves screening against embryos with extra or missing chromosomes are thought to have an increased risk of implantation failure (Simoncelli, 2003). Ethical issues on PGD are an important aspect. Though PGD may help couples with serious genetic disorders to screen for defects, it is not a 100 percent reliable procedure. Hence it is an unnecessary burden on them. Besides, discarding the embryos after detection of some small genetic problem which could be later solved through treatment is also a concern. The process of PDG may also result in wastage of embryos and once the PGD is done on the embryo, the future consequences of this procedure is also no completely studied. Hence, PGD need to be restricted and should be administered only on high risk couples. References American Society of Reproductive Medicine (1994) Ethics Committee, Ethical considerations of assisted reproductive technologies. Fertil. Steril. (Supplement), 62, 32S-37S. ASRM, (2001). Preconception gender selection for nonmedical reasons. Fertility and Sterility 75(5): 861-864. ASRM, (1999). Sex selection and preimplantation genetic diagnosis. Fertility and Sterility 72(4): 595-598. Fukuyama, F. (2002). Our Posthuman Future: Consequences of the Biotechnology Revolution Farrar, Strauss and Giroux, New York, USA. Hansen, M., J.J. Kurinczuk, C. Bower, and S. Webb, (2002). The risk of major birth defects after intracytoplasmic sperm injection and in vitro fertilization. New England Journal of Medicine, 346: 725-730. Institute for Reproductive Medicine and Genetic Testing, (2002). [Online] Available from http://www.preimplantationgenetictesting.com/Cancer_of_Breast.htm, http://www.preimplantationgenetictesting.com/Cancer_Prevention.htm [Accessed January 19, 2007] Kass, L. R. (2002) Life, Liberty and the Defense of Dignity: the Challenge for Bioethics. Encounter Books, San Francisco, USA. Lynn R. (2001). Eugenics: A reassessment. Westport, CT: Praeger Publishers. p 366. Pregnancy-Info.net. (2005) Preimplantation Genetic Diagnosis. [Online] Available from http://www.pregnancy-info.net/infertility_pgd.html [Accessed January 17, 2007]. Robertson, J.A. (2003) Extending preimplantation genetic diagnosis: the ethical debate. Human Reproduction, Vol. 18, No. 3, 465-471. Schieve, L.A., S.F. Meikle, C. Ferre, H.B. Peterson, G. Jeng, and L.S. Wilcox. (2002). Low and very low birth weight in infants conceived with use of assisted reproductive technology. New England Journal of Medicine 346: 731-737. Simoncelli, T.M. (2003) Pre-Implantation Genetic Diagnosis: Ethical Guidelines for Responsible Regulation. [Online] Report Submitted to the President’s Council on Bioethics by The International Center for Technology Assessment. Available from http://www.icta.org/doc/pgd%20guidelines.pdf [Accessed January 19, 2007]. Stock, G. (2002). Redesigning Humans: Our Inevitable Genetic Future. Houghton Mifflin, New York, USA. Towner, D. and RS Loewy, (2002). “Ethics of preimplantation diagnosis for a woman destined to develop early-onset Alzheimer Disease.” JAMA,Vol. 287. Read More