Preimplantation genetic diagnosis and savior siblings: ethical implications

Preimplantation Genetic Diagnosis: State of the Art

Preimplantation genetic diagnosis (PGD) is used to analyze embryos genetically before their transfer into the uterus and offers couples at risk the chance to have an unaffected child, without facing termination of pregnancy. Embryos are obtained by in vitro fertilization with intracytoplasmic sperm injection (ICSI), and are biopsied mostly on day 3; blastocyst biopsy is mentioned as a possible alternative; the genetic analysis is performed on one or two blastomeres, by fluorescent in situ hybridization (FISH) for cytogenetic diagnosis, or polymerase chain reaction (PCR) for moleculardiagnosis (Basille, et al., 2009). PGD requires a close collaboration between obstetricians, fertility specialists, IVF laboratory and human geneticists. It needs intensive effort, expensive techniques and is demanding for the patients, but it offers tremendous opportunity for couples whose previous child has exhibited genetic abnormalities.

Children as Hematopoietic Stem Cell Donors

This article isn't directly related to PGD but, based on the last article, it seemed relevant to find information on the ethical implications that are relevant to using PGD to generate umbilical cords for older siblings. Children often serve as hematopoietic stem cell donors, most commonly for their siblings. HLA-matched biological siblings are generally preferred as donors because of reduced risks of transplant-related complications as compared with unrelated donors (Committee on Bioethics, 2010). Whereas bone marrow transplant and peripheral blood might be controversial, the umbilical cords are relatively less of an ethical challenge. PGD could actually ensure that the umbilical cord meets the HLA properties of their siblings and could serve as a viable option for a variety of diseases. In 1990, Abe and Mary Ayala became the first successful publicized case in which a family sought to conceive a child (Marissa) to save another child (Anissa) and there have been later cases where PGD contributed to the HLA matching.

Preimplantation genetic diagnosis at 20 years

PGD has evolved into not simply an earlier extension of traditional prenatal genetic diagnosis, but a modality offering novel indications. PGD can be applied for any Mendelian disorder whose location is known, using linkage analysis even when the causative mutation is not known. More than 200 different conditions have been tested, with high accuracy and safety (Johnson, 2010). The advancements in the field have and the new capabilities that are available have made many call for a new approach to the ethical considerations that are now feasible.

Preimplantation genetic diagnosis for monogenic diseases: overview and emerging issues

The development of multiplex fluorescent PCR allowed the testing of many linked markers along with the mutation test, which has vastly increased the accuracy by controlling for contamination and identifying allele drop-out and the advent of highly effective whole genome amplification has open a wide array of different possiblilites that can take advantage of technologies such as preimplantation genetic haplotyping and microarrays which increase the ability to catch any genetic defects (Renwick & Ogilvie, 2007). However, these discoveries have also come with unintended consequences. Although it has led to the controversial "savior baby," it has also opened the door to "reproductive tourism" since different countries have different regulations surrounding these practices.