Reuven Brandt on anonymity and mitochondrial donation

Brandt, Reuven

LSE Research Online

Genetic Fallacies?Reuven Brandt on anonymity and mitochondrial donationMuch ethical debate has surrounded the UK’s recent decision to permit the use of mitochondrialtransfer techniques in human subjects. What makes mitochondrial transfer ethically controversial isthat while mitochondria are organelles found in the cytoplasm of cells, they contain their own DNAthat is distinct from the DNA found in the nucleus of cells. Consequently, the children createdfollowing mitochondrial transfer end up inheriting DNA from three individuals—the mitochondrialdonor as well as the individuals who provide the usual maternal and paternal contributions of DNA.The media’s treatment of the subject has tended to focus on whether mitochondrial transfertechniques are a kind of genetic modiﬁcation that we should eschew on principle, and whether thecreation of so-called ‘three-parent babies’ is the thin-edge-of-the-wedge into an era of wide-spreadhuman genetic engineering. While these are indeed interesting and important questions, here Iwant to focus on a more narrow policy question given that mitochondrial transfer has beenapproved for human use in the UK. That question is whether mitochondrial donors ought to beconsidered akin to gamete donors (donors of sperm and eggs whose nuclear DNA is passed on tooffspring) when it comes to children’s right to access identifying information about their ‘genetic’parents.While UK law permits children created using donor gametes to apply for access to identifyinginformation about their donor(s) once they reach 18, no such right has been extended toinformation about mitochondrial donors. I think that this decision to permit anonymousmitochondrial donation is the right way to go—for the record, I also think that anonymous spermand ova donation should be permitted, but that is a separate issue. However, I also think that thearguments offered in its defence have been rather weak. After brieﬂy explaining why I take issuewith the arguments in favour of anonymous mitochondrial donation that have been offered so far, Iwill then offer some reasons for why we are justiﬁed in treating mitochondrial donation differentlythan gamete donation when it comes to anonymity. Before getting to the arguments though, I willﬁrst give a bit of background biology that will help illustrate why the question of donor anonymityarises in the ﬁrst place.While most of our DNA resides in the nucleus of our cells, a small portion (37 of the approximately30,000 genes that makeup the human genome) resides in mitochondria. Whereas nuclear DNA isalmost identical in all cells of the body, individuals can have multiple different mitochondrialgenomes, even in the same cell. The ratio of different mitochondrial variants can differ from cell tocell. Additionally, while an individual’s nuclear DNA is a mix of paternal and maternal nuclear DNA,individuals’ mitochondrial DNA is made up from the particular mix of mitochondrial genomes foundwithin the mitochondria of the ovum from which they developed. Consequently, mitochondrial DNAinheritance is strictly maternal, but offspring can have a different ratio of mitochondrial DNAvariants than their mothers, depending on the distribution of mitochondrial variations present in aparticular ovum.We might think that mitochondrial donors are somewhat similar to gamete donors because theypass on some of their DNA to the children they help create, and this mitochondrial DNA can in turnbe passed along to future generations—at least in the case of female offspring. If the legal right toknow identifying information about one’s progenitors is grounded in genetic relatedness, then thereseems to be a prima facie case to treat mitochondrial donors like gamete donors with respect toanonymity.Proponents of mitochondrial donor anonymity (for example, the Human Fertilisation andEmbryology Authority (HFEA) and the Nufﬁeld Council on Bioethics) have advanced two principlearguments for why anonymity should be permitted in the case of mitochondrial donation, eventhough it is not permitted in the case of sperm and egg donation. The ﬁrst is that the DNA inmitochondria does not encode resemblances in personal characteristics between donor andresultant child, and the second is that mitochondrial donation does not establish a unique geneticlink between donor and progenitor. However, both these justiﬁcation are vulnerable to seriousobjections.First, consider the claim about resemblances between mitochondrial donors and resultantoffspring. While neither the HFEA or the Nufﬁeld Council offer a clear deﬁnition of ‘personalcharacteristics’, we can safely presume that certain traits, like those effecting personality andbehaviour, would likely count. The strength of this ﬁrst argument thus rests on what the biologicalsciences say about the role mitochondrial DNA plays in the development and transmission ofthese traits.Though our understanding of the role mitochondria play in complex traits (like personality,cognitive ability, and so on) is in its infancy, there is some evidence suggesting that mitochondrialDNA may inﬂuence extraversion, susceptibility to certain degenerative neurological disorders, andsusceptibility to certain psychiatric disorders. To be clear, I am not suggesting that there isdeﬁnitive evidence that mitochondrial DNA is involved in these characteristics, only that it is stillvery much an open question. If it turns out that mitochondrial DNA is in fact important in thedevelopment of complex traits, then mitochondrial donation may very well result in certainresemblances between donors and their offspring. My chief worry about this argument then is thatit rests on empirical claims about the phenotypic effects of mitochondrial DNA that remain to besettled.The second argument, that anonymous mitochondrial donation is permissible because no uniquegenetic connection is established between donor and offspring, suffers from a theoreticalweakness rather than an empirical one. No deﬁnition of ‘unique genetic connection’ is provided,but presumably what the Nufﬁeld Committee has in mind is something like the following: sincemitochondrial DNA is strictly maternally inherited, all of a mitochondrial donor’s close maternalrelations will have very similar mitochondrial DNA. Consequently, any child that receivesmitochondria from a donor in fact receives particular mitochondrial DNA that is common toindividuals other than the donor.The chief problem with this argument is that it seems that lack of a unique genetic connection doesnot alter any right to access identifying information about a genetic progenitor. For instance,imagine that a sperm donor is one of a set of monozygotic (identical) triplets. Any nuclear DNA thatsubsequent child inherits from this donor is also common to the donor’s monozygotic siblings;however, this does not seem to diminish the child’s right to identifying information about the donor.It would seem wrong to give most donor-conceived children access to identifying information abouttheir gamete donor, while denying this information to donor-conceived children whose donorhappens to have a monozygotic sibling.Though these two arguments do not succeed in showing that we ought to treat mitochondrialdonors differently from gamete donors when it comes to anonymity, we can still be consistent whilepermitting anonymous mitochondrial donation but not anonymous gamete donation. This isbecause many of the arguments advanced against donor anonymity in the case of gametedonation do not equally apply to mitochondrial donation. Though I cannot go through all thearguments here, I think the following examples are sufﬁcient to shift the burden of proof to thosewho think that anonymity should not be permitted in mitochondrial donation.First, consider David Velleman’s claim that contact with one’s genetic relations is importantbecause crucial self-knowledge is gained through contact with those whom we resemble. On hisview, disclosure of identifying information would be important as a (perhaps distant) ‘second best’to being raised by one’s genetic parents because it at least offers an avenue for children to attemptto initiate contact with their progenitors later in life. Even if we grant Velleman his controversialview about self-knowledge and genetic ties, there is still reason to the think the case for disclosureis much weaker in the case of mitochondrial donation. This is because even though mitochondrialDNA may result in resemblances that are important to self-knowledge, the majority of inheritedtraits are likely transmitted via nuclear DNA. Furthermore, children created using donormitochondrial DNA are likely to be raise by their nuclear DNA progenitors—the main purpose ofmitochondrial donation, after all, is to allow women to have genetically related children whileminimizing the risk of transmitting mitochondrial disease to their offspring. Consequently, a childcreated using donor mitochondria will likely still develop intimate relationships with the geneticprogenitors responsible for the vast majority of their inherited traits. Given that there is less of aloss of the crucial good—namely, self-knowledge—it may well be the case that other interests,such as those of the intending parents and mitochondrial donors themselves, supersede theinterests of children to have access to identifying information about their donor.Second, if we think that any harms that might arise from lack of knowledge about one’s geneticprogenitors are socially constructed rather than grounded in biological facts, there are alsoreasons to think that there will be substantial asymmetries between gamete donation andmitochondrial donation. Consider that up until recently it has not been possible to separate thetransmission of the maternal complement of nuclear DNA from the transmission of mitochondria,nor has any importance been traditionally placed on mitochondrial inheritance. Both the HFEA andNufﬁeld reports, for example, state that mitochondrial donation ought to be seen as different in kindfrom standard gamete donation when it comes to disclosure of information. By contrast, in theWest, rearing arrangements that involved individuals other than a gestational mother and thechild’s genetic father carried with them certain stigmas for both the parents (for example, shameand condemnation associated with reproduction outside of marriage) and child (for example,illegitimacy, and its legal and social consequences). It is thus unclear whether any sociallyconstructed desire ‘to know’ and related frustration and distress some children created via donorgametes experience will equally arise in children created via donor mitochondria. We cannotsimply assume that the experience of children created via anonymous mitochondria donation willparallel that of children created as a product of anonymous gamete donation. Consequently,arguments against anonymous gamete donation that are based on the emotional distress reportedby children who have a deep desire ‘to know’ cannot be extended a priori to anonymousmitochondrial donation.What I hope I have managed to show is that while two inﬂuential arguments offered in favour ofmitochondrial donor anonymity are not fully convincing, there other reasons to think that we canpermit mitochondrial donor anonymity while at the same time reject anonymity in gamete donation.Monday, 6 June 2016Share This Story, Choose Your Platform!Related PostsReuven Brandt is a Research Associate at Lancaster University, working on a project entitled ‘TheDonation and Transfer of Human Reproductive Materials’. This post is based upon his work for thisproject, as well as his article ‘Why Disclosure of Genetic Ancestry in Misattributed Paternity CasesShould Be Treated Differently from Disclosure in Adoption and Gamete Donation’ published in theAmerican Journal of Bioethics. His research focuses on issues at the intersection of philosophy,bioethics, and law. Image credit: Andy Leppard, ‘DNA Representation‘Powered by TCPDF (www.tcpdf.org)

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