Bioethics in the News A brief introduction to two recent developments in bio-technology – gene or genome editing and Non-invasive Prenatal Testing.

Gene or Genome Editing

While gene editing technologies have been around for several years, a new technique has recently been developed that is cheaper and more efficient than earlier technologies. Known as CRISPR-Cas9, this technique enables faulty sections of DNA to be located, then ‘cut’ out and either replaced with a healthy copy or inactivated. Gene editing could in future be used to treat single gene inherited conditions, such as cystic fibrosis and sickle cell anaemia, and in the treatment of diseases such as HIV and cancer. It also has the potential to be used with crops, for example to develop disease resistance or to increase crop yields that use less water, and in livestock to improve certain advantageous traits.

Recently it was reported that scientists in China had edited the genomes of human embryos, and earlier this year researchers in the United Kingdom were given permission to modify human embryos in order to better understand the causes of miscarriages. However, there is some disquiet about the use of these techniques for humans. Apart from concerns regarding the unknown effects of germline modification on later generations, there is concern that gene editing will be used to ‘enhance’ humans. Scientists and bioethicists are debating whether or not there should be some moratorium on human gene modification until safety issues are resolved, and there has been a thorough examination of the broader social and ethical issues concerning human ‘enhancement’, such as ableism and disability, as well as economic and health inequalities.

In 2000 the New Zealand Catholic Bishops noted in their submission to the Royal Commission on Genetic Modification that human dignity must be ordered to the integral good of the human person as well as respecting the integrity of other species and of all creation. They specifically noted that they did “not see the technology of genetic modification to be in conflict with ethical values“ so long as “safety issues are resolved within acceptable limits of risk.” These limits include proper respect for the innate dignity of human life which excludes all forms of destructive research involving human embryos. 

Non-invasive Prenatal Testing

While prenatal screening is currently available in New Zealand, the development overseas of a maternal blood test known as NIPT (non-invasive prenatal testing) that can more accurately detect some foetal chromosomal abnormalities has raised the issue of whether it should be publicly funded in New Zealand (it is currently available privately for payment). NIPT is able to analyse the small amount of cell-free DNA in maternal blood that comes from the placenta, and which mostly (98% of cases) matches the DNA of the foetus. This has meant that a blood sample taken from the mother can be analysed for the presence of certain chromosomal abnormalities, which include trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome).

The test is a screening test, not a diagnostic test, as it indicates only the probability of a trisomy pregnancy and a follow-up invasive test is still required to confirm results. It also has certain limitations: It was originally validated on a population of high-risk women so the sensitivity of the test on the low-risk population is unknown. For this reason it is usually offered only to women who are in the ‘high risk’ group. It is also known to be less accurate when maternal weight is high and its accuracy in multiple gestation pregnancies is unknown.  The ease of use and safety of non-invasive testing is likely to lead to increased requests for testing and potentially the provision of free national screening. Because there is no ‘cure’ for these conditions, the reasons for informing mothers are to either enable them to begin to adjust to and make plans for living with a child with a disability, or for eugenic purposes, that is to enable them to seek a termination of the pregnancy.

The very availability and use of such screening carries an implicit message that raising a child with a disability is a burden both on the family and society, one that can be avoided. In France, the United Kingdom, Spain and Italy, between 90 and 95 percent of foetuses affected by Down syndrome, detected using current prenatal diagnostic techniques, are aborted. One of the consequences of the increasing use of pre-natal testing is that it introduces ‘eugenics’ by stealth, that is, without a proper debate taking place about  the desirability or ethics of preventing the birth of babies with certain detectable conditions.