Designer babies
Milo Fabian
The issue of embryonic screening has been a matter over which there has been a large amount of fevered debate. People, as with the indomitable rise of genetically modified (GM) crops, are scared of what can be interpreted as the ÂGod complexÊ of geneticists. People are frightened that this element of selection will lead to a genetically stratified dystopian society, based on an individualÊs genetic traits. In this essay, I will endeavour to test the validity of that belief by exploring the possibility of advanced embryonic selection and, by means of ethical examination, studying whether or not the very act of embryonic and genetic selection poses a risk to society as a whole. Embryonic screening can be carried out during the process of in vitro fertilization (IVF). The genomes of embryos created by IVF can be sequenced in part or entirely in order to determine whether they contain detectable genetic abnormalities. This is done to provide the parents with a greater probability of a successful implantation and pregnancy, reducing the likelihood of a miscarriage and of the child having a postnatal genetic disorder. It is believed that a significant proportion of the failed attempts to implant and other failures in IVF are due to aneuploidy, an embryo having the incorrect number of chromosomes in its genetic code. Therefore, techniques are sought which aim to assess the chromosomal number before implantation into the motherÊs uterus. One such technique is a pioneering new method, involving extracting the DNA of embryos that are only about 3 days old, then using a technique called next-generation sequencing (NGS) to break up their The science
genomes into sections, and determining chromosomal abnormalities from the data collected. NGS involves using DNA helicase to ÂunzipÊ, or separate, the strands of the DNA double-helix structure from one another, and the passing of individual nucleotides across the structure of the DNA in the presence of DNA polymerase. When the correct complimentary base pair (i.e. A, T, C, or G) attaches to the DNA single strand, it releases a few H + ions, reducing the pH of the system. The base pair that has attached can be determined from how much the pH drops and therefore the complimentary base pair must be present on the original strand of DNA from the embryoÊs genome. This technique is held to be the fastest, most cost-effective method of sequencing embryonic genomes, which still maintains a high level of accuracy. The need for the sequencing to be fast – ideally under 24 hours – is owing to the fact that the embryos have a very high rate of mitotic division. This means that, while the DNA of the embryo is being examined on Day 3 after fertilization, the embryo is still developing rapidly, and by the fifth day an embryo must be implanted if there is to be a reasonable chance of success at embedding the embryo in the uterine wall. After the fifth day, you run the risk of the embryo becoming too developed or the uterus becoming too hostile for successful implantation. Genetic selection at the moment is limited to gender and potentially eye and hair colour, but with a large degree of error. These genotypic quantities can only be chosen in the embryo if they are contained within the genetic codes of the biological parents of the embryos. Therefore, any selection will serve only to combine the best features of the childÊs parents. This is the
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