11 April 2016
Senior Research Fellow, Division of Health Sciences, Warwick Medical SchoolAppeared in BioNews 846
In February 2016, the UK's first licence to use CRISPR/Cas9 genome-editing techniques in human embryo research was granted to Dr Kathy Niakan of the Francis Crick Institute, London (see BioNews 837). The decision sparked further debate on this controversial topic (see BioNews 833 and 836).
While the technology allows for precise 'editing' of the human genome at the single nucleotide level – signalling its potential to eradicate inheritable diseases – the attendant social, ethical and legal implications of the technology are complex. While the licence granted to Dr Niakan is limited (transfer of the edited embryos for gestation is strictly prohibited under its terms), the decision to grant the license in the first place was interpreted by some as the first step towards permitting so-called 'genetically modified' babies, as well as a permanent modification of the human germline.
Important questions have been raised, however, in the dialogue surrounding the licence application, particularly around how we understand and define identity, difference, as well as the nature and quality of human life.
One objection, which lies at the very heart of the genome-editing debate, focuses on the physical and symbolic relationship of our genetic make-up to our sense of identity. Unlike prenatal testing or pre-implantation genetic diagnosis (PGD), which rely on the principles of detection, selection and/or elimination of embryos or fetuses affected by genetic diseases, genome editing is so controversial because, when used on a mass scale, it has the potential to entirely remove particular genetic diseases from the human germline.
While carriers of genetic disease might still be born following the use of prenatal testing, by altering the genetic sequence of an embryo through genome editing, the genetic disease would be entirely removed from that family's bloodline. On a mass scale, this could translate to the complete removal of the disease from the human gene pool.
This possibility has been heralded as progress by many (see BioNews 838), but my recent research Imagining Futures: the social and ethical implications of genetic screening, calls into question some of the assumptions underlying the belief that genetic disease is, inherently and by its very definition, a trait to be avoided (1). Through in-depth interviews and a nationwide survey of families living with one particular genetic disorder – Spinal Muscular Atrophy – I set out to explore attitudes towards genetic screening among people whose lives are most intimately affected by genetic disease.
Spinal Muscular Atrophy (SMA) is a neuromuscular genetic condition, associated with generalised muscle weakness and respiratory complications. It is associated with a wide spectrum of severities, divided into 'types' (0-IV). The most severely affected children (type 0/I) usually have poor life expectancies (typically less than 18 months) due to the severity of their respiratory symptoms. For others (types II, III and IV), SMA can present as a 'liveable' disability, meaning that although it results in (often significant) impairment, it does not preclude a long and satisfying life (see BioNews 732).
Screening for SMA is controversial among affected families, not least because current genetic testing technologies cannot accurately predict where on this spectrum of severity a future child's SMA will be. Indeed, whilst 75 percent of survey respondents supported some form of population-level genetic screening programme for the condition, the study also uncovered undertones of ambivalence and contradiction in participants' responses.
At the heart of this ambivalence lay contrasting views about termination of pregnancy for SMA across the spectrum of severities, as well as the impossible tension between both wanting to preserve the lives of affected (but otherwise wanted) fetuses, but simultaneously wishing to avoid the condition. Screening, when used in conjunction with selective termination or PGD, raises difficult decisions for precisely that reason – it enables selection against, or avoidance of, the condition, but at the cost of that specific embryo/fetus. In this context, reproductive decisions become all or nothing.
Embryonic genome editing completely alters the screening debate because it suggests the possibility of circumventing this dilemma. By removing the condition through editing, but keeping the future child, genome editing appears to forge a new pathway through the morally precarious terrain of reprogenetic decision making.
Arguably, genome editing is more easily defended against some of the critiques levied by disability-rights supporters, particularly those raising 'expressivist' concerns (i.e the idea that prenatal testing, and selective termination where genetic differences are detected, communicates a negative valuation of people living with the tested-for conditions and disabilities more broadly) (2). According to this line of argument, in the context of prenatal testing, the disabling trait becomes the most important thing there is to know about that particular fetus; the trait 'obliterates' the whole (3).
In the scenario of embryonic genome editing, however, the disabling trait, while still deemed to be in need of removal, no longer overrides the value of the (future) child's life. In principle this may sound like a convenient solution to a heavy ethical and philosophical dilemma, but important questions still remain; by removing the condition, is it the same child? What else, if anything, do we lose when we edit out genetic disease?
The message from families living with SMA is clear. SMA not only fundamentally shapes the lives, identities and worldviews of the people diagnosed with it, but also those of the entire family. No one is left unchanged by the experience of having a child with SMA born into the family. Moreover, through the survey and interviews conducted as part of the Imagining Futures study, it was clear this was never a straightforwardly negative experience but, rather, a highly complex interaction of positive and negative experiences that shifted and changed in meaning over time. Indeed, for the 25 percent of survey respondents who did not support any form of screening for the condition, the idea that fewer children with SMA coming into the world would be a loss to society was a key reason for their non-support.
As embryonic genome editing advances, it is vital that the voices of families living with the very genetic diseases it could be targeted towards are heard in the surrounding debates. Indeed, it is their lives and their stories that offer us the most valuable insights into not only what we would gain through the removal of genetic disease from the human germline but, critically, what we also stand to lose.