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  • 02May

    Is it Our Right to Genetically Engineer Our Offspring? Discussing ‘Three Parent Babies’

    Under UK law, we have had the right to use assisted reproductive technologies (ARTs) to select for embryos without a genetic defect for many years now. If unassisted conception is likely to result in extreme suffering and/or a severely shortened lifespan and has a very clear-cut genetic cause, it is probably eligible. Specific information on eligible disorders is available though the UK Human Fertility and Embryology Authority website.

    Through use of sex-selection techniques, female embryos may be selected for, thus avoiding birthing males with X-linked disorders such as Duchenne Muscular Dystrophy. We can also use pre-implantation genetic diagnosis that allows for the implantation of embryos of either sex that do not carry a specific genetic defect, thereby avoiding passing on diseases like Cystic Fibrosis and Huntington’s Chorea [1]. There is even an ART known as cytoplasmic transfer (CT) designed to prevent birthing children with a mitochondrial disease. Mitochondrial disease affects 1 in every 6500 babies born in the UK each year and results in muscle weakness, blindness, heart disease and a shortened lifespan. In CT, donor cytoplasm containing healthy mitochondria is injected into the mother’s egg containing the defective mitochondria and IVF is performed thereafter as usual [2]. However this was later banned in the US and never licensed for use in the UK. Instead, in the UK we are now replacing this technology with an updated version, a decision that has proven to be quite controversial.

    “Three-parent babies”; “three-parent IVF”; “genetically modified babies”; three useless albeit media-friendly terms amongst many others that tell the public nothing about the procedure. If the old technology is called “cytoplasmic transfer” then we should name its replacement “nuclear transfer” rather than any of the other terms. In this updated procedure, the nucleus is taken from the donor egg and discarded before the nucleus of the mother’s egg is transferred in as a replacement. Here’s the catch… Mitochondria, a separate organelle to the nucleus, has it’s own DNA and this is what has caused the “three parent:” uproar, the concept that you can be genetically three people rather than the normal two. This is frankly misinformed on many levels.

    Firstly, if changing the mitochondria changes the genetic background of a person giving them three parents, then there are already people resulting from “three parent” IVF alive on this planet! In CT extra set of mitochondria is placed in the egg prior to fertilisation. One such ‘3-parent IVF’ patient born through CT is Alana Saarinen; a healthy teenager born in 2000 with no known medical conditions [2, 3].

    Secondly, the existence of mitochondrial DNA (mtDNA) is hypothesised to be vestigial from ancient mitochondria originally being separate single-celled organisms, probably similar to modern bacteria. These bacterial organisms are thought to have formed a mutually beneficial symbiosis with bigger single-celled organisms before eventually being encapsulated and made part of the ancestral eukaryotic cell [4]. Actually, this isn’t the only example of possible bacterial-origin of our DNA; we carry hundreds of thousands of DNA fragments that we have inherited from bacteria and a recent study has shown us to carry approximately 150 full genes that are bacterial in origin [5]. Even now, we continue to inherit fragments of DNA as we go along from bacteria and they do not make us any less human [6]. Why should a tiny ex-bacterial piece of DNA that serves only to control itself make us any less one person’s child or any more another?

    Thirdly, DNA testing uses the genomic DNA (gDNA) originating from the nucleus, not mtDNA, so paternity/maternity testing would still be valid. It would still show the father who provided the sperm as the father, the mother who provided the egg nucleus as the mother and the egg donor wouldn’t even be noted. Plus there are plenty of individuals born from donor eggs and/or sperm, so using DNA to argue about the identity of a family or individual is a moot point at best.

    Finally, there’s a huge difference between the roles of mtDNA and gDNA. A tiny number of genes are contained within the mtDNA accounting for 0.1% of the total genome. All of these genes are mitochondrial specific – they only control what the mitochondria do. Therefore, changing the mitochondrial genetic background by replacing the mitochondria won’t affect any other part of the developmental processes; it will only alter the function of the mitochondrion in its role of converting oxygen and sugar to energy. Similarly, a change in the cells’ mtDNA will not lead to designer babies as the very things typically mentioned as being “desirable” traits – hair and eye colour, intelligence, height, etc. – are all contained within the gDNA and sit in the chromosomes.

    One parent that would’ve benefitted from the introduction of this technology much sooner is Sharon Bernardi. Sharon has given birth to seven children, each one of them affected by mitochondrial disease. Each one of them suffering and unfortunately dying young. Sharon’s fourth child, Edward was helped by doctors who intervened to prevent him dying as a newborn from the same type of blood poisoning that killed his siblings. However, surviving this resulted in Edward suffering spasms lasting hours and inordinate amounts of pain later in life. Edward survived to adulthood before dying aged 21. As Sharon said to the BBC, “I don’t think I am selfish, I wanted my child to be healthy” [7].

    Asked in the headline of this article is whether or not it is our right to genetically engineer our offspring. As the ethical debate here should never have been about familial identity nor about designer babies, lets rephrase this question.

    Do we have the right to bring children into this world that will suffer inordinate amounts of pain prior to the end of their very short lives when we have methods of avoiding this by selecting against the established genetic cause?

     

    By Claire Ozber, Alumnus writer; BSc (Hons) Genetics (University of Leeds), MSc Molecular Medicine (University of Sheffield)

     

     

    Image: modernreaders

     

    References

    [1] Human Fertilisation & Embryology Authority: Pre-implantation Genetic Diagnosis http://www.hfea.gov.uk/preimplantation-genetic-diagnosis.html

    [2] CNN Health: How Far Will Couples Go To Conceive? http://edition.cnn.com/2004/HEALTH/03/12/infertility.treatment/index.html?iref=allsearch

    [3] BBC: The Girl With Three Biological Parents. http://www.bbc.co.uk/news/magazine-28986843

    [4] Gray MW (2012). Mitochondrial Evolution. Cold Spring Harbor Perspectives in Biology. Accessible at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3428767/

    [5] Science Magazine: http://news.sciencemag.org/biology/2015/03/humans-may-harbor-more-100-genes-other-organisms

    [6] Mills RE et al. (2007). Which Transposable elements are active in the human genome? Trends in Genetics. Accessible at: http://www.ncbi.nlm.nih.gov/pubmed/17331616

    [7] BBC: The woman who lost all seven children. http://www.bbc.co.uk/news/magazine-19648992

Discussion 2 Responses

  1. September 30, 2016 at 5:57 am

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  2. October 15, 2016 at 7:57 am

    There is, however, another form of genetic engineering of human embryos. This is the one that the US tried and then banned, and that the British government recently opened licensing applications for. And what s probably more important for the future of the debate is how Britain decided the technology works and is safe.

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