Bioethics in Faith and Practice, Volume 4, Number 1

17 Bioethics in Faith and Practice ⦁ 2019 ⦁ Volume 4 ⦁ Number 1 New combinations of gametes Over the last few years, numerous studies have explored the possibility of new combinations of gametes to form an embryo, eliminating the need for either sperm or egg. For instance, in 2001, Australian scientists successfully injected somatic cells into mouse eggs to form embryos, although developmental viability was limited. 41 In 2016, scientists from the University of Bath demonstrated that parthenogenotes (unfertilized eggs that are tricked into developing like an embryo while remaining haploid) are capable of being fertilized by sperm; authors posited that any somatic cell with half its genetic material removed should be able to undergo the same process, removing the need for an egg. 42 In 2017, University of Cambridge scientists used embryonic mouse stem cells to mimic in-vitro embryogenesis. 43 In 2018, a study published in the journal Nature performed a similar process with human stem cells to produce a “blastocyst-like structure.” 44 If this technology were to be developed and popularized, the requirement for both male and female genetic parents could be eliminated, further changing the historically fundamental structure of family and kinship ties. Preimplantation genetic diagnosis and selective implantation Preimplantation genetic diagnosis, or PGD, has been used in conjunction with IVF since 1990. 45 It’s a form of genetic screening that allows physicians to detect monogenic (Mendelian) diseases, conditions which result from one or a very few mutations at known loci in the genome. Records are unclear on how common PGD is in the United States, but the practice is often recommended for couples with a history of genetic disease. 46 Background DNA for PGD can be obtained at several stages of early development, including before the embryo is even formed. Polar bodies, the inert cells created alongside the egg during meiosis, can be safely removed and examined for aneuploidy, 47 the condition of having the incorrect number of chromosomes due to nondisjunction. Aneuploidy in a polar body often but not always indicates aneuploidy in the egg, which typically results in a failed pregnancy. This is a common problem for older women trying to conceive. 48 Examining polar bodies for some monogenic diseases has also been used to deduce the genotype of the egg with up to 97% accuracy. 49 Polar body biopsy may allow higher rates of pregnancy while avoiding some of 41 Orly Lacham-Kaplan, Rob Daniels and Alan Trounson, "Fertilization of Mouse Oocytes using Somatic Cells as Male Germ Cells," Reproductive BioMedicine Online 3 (2001), 205-211. 42 Toru Suzuki et al., "Mice Produced by Mitotic Reprogramming of Sperm Injected into Haploid Parthenogenotes," Nature Communications 7 (2016), 1-15. 43 Sarah Ellys Harrison et al., "Assembly of Embryonic and Extraembryonic Stem Cells to Mimic Embryogenesis in Vitro," Science 14 (2017). 44 Nicolas Rivron et al., "Blastocyst-Like Structures Generated Solely from Stem Cells," Nature 557 (2018), 106-111. 45 Niederberger, "Forty Years of IVF," , 185-324 46 Susannah Baruch, David Kaufman and Kathy Hudson, "Genetic Testing of Embryos: Practices and Perspectives of US in Vitro Fertilization Clinics," Fertility and Sterility 89 (2008), 1053-1058. 47 Markus Montag et al., "Polar Body Biopsy," Fertility and Sterility 3 (2013), 603-607. 48 Marie MacLennan et al., "Oocyte Development, Meiosis and Aneuploidy," Seminars in Cell and Developmental Biology 45 (2015), 68-76. 49 Karen Sermon, André Van Steirteghem and Inge Liebaers, "Preimplantation Genetic Diagnosis," The Lancet 363 (2004), 1633-1641.