Editing Human Embryos: The Science And The Ethics

Jonathan James

For a long time, the much discussed idea of editing human embryos to eradicate genetic defects has been seen as something of an extremely controversial pipe dream. Until recently, scientists had been unable to successfully edit the genome of a human embryonic cell, both for scientific and ethical reasons. That is until recently, when a team lead by researcher Junjiu Huang at the University of Guangzhou in China announced in the journal Protein and Cell that they had successfully edited out the gene for β-thalassaemia, a condition that affects the production of oxygen-carrying haemoglobin in the blood. However, it is important to note that this was only successful in a couple of a total of 78 cells used, all of which had been designed so that they could not develop into viable offspring. Due to the low success rate, Huang’s team have stopped further work, believing that at the moment the techniques are too inefficient to have any practical real world applications.

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Image Credit: Public Domain Pictures

The technique itself relies on a system called CRISPR/Cas9. This technique works by targeting a specific DNA sequence within the cell’s genetic makeup, and specifically cutting it out, replacing it with a correct copy of the gene, or an inactive, neutral replacement. It, along with all such similar techniques, are very inefficient, although a more recent development, TALENS, promises to reduce this inefficiency.

Of course, the controversial side of this development is not the science itself, but the ethical implications. For some, gene editing in this way is seen as a fantastic opportunity to combat disease; for others it only creates an ethical minefield. So who exactly is right, if anyone?

On the one hand, if restricted to specific cases, there is great hope that gene modification in this way will allow us to overcome all manner of genetic disorders, from Huntington’s disease to cystic fibrosis, by simply removing the offending gene from the developing embryo. George Church, a geneticist at Harvard Medical School, sees no issue once the practical problems have been solved. The fact that manipulation in this way will be passed onto to offspring (via the germ line – sex cells; sperm and egg.) is of little consequence, as Craig Mello of the University of Massachusetts believes altered germ lines will ‘protect humans against cancer, diabetes and other age-related problems’ in the future.

Yet one issue remains – the wider effects of such widespread alteration to our genes. It is incredibly difficult to assess what impact modifying a particular gene might have on the next generation – a risk many consider too great. After all, what good would it be if you remove risk factors for diabetes, only for that individual’s offspring to develop another disease like cancer?

What most scientists (and the wider public at large) agree on is the need for a serious discussion over the use of this technology. Many argue that altering embryos in this way goes too far, beyond what can be considered ethically correct. Edward Lanphier, president of pharmaceutical company Sangano, believes there are ‘fundamental ethical issues’ involved, concerned that the techniques could be exploited for ‘non-therapeutic modifications’ such as eye colour and hair. This underlies a familiar argument in genetic manipulation – the development of so called ‘Designer babies’ – infants that have been specifically designed by their parents and scientists to have specific traits; whether it be increased intelligence or a specific appearance.

So where do you stand on the ethics? For many, this is a very divisive topic. Clearly it offers the potential for great benefit – helping people, who would otherwise be resigned to suffering at the hands of a particular genetic disease, the chance at a happier life. And still there are enormous ethical and moral problems which need to be understood if not solved. Yet it is worth remembering just how remarkable it is that we are now on the brink of having the ability to directly change the way humans are coded. With each passing day, scientists are developing a better and better understanding of the way genes influence our lives. So even if we end up disagreeing on whether it’s right or wrong, let’s all appreciate just how amazing it is that we can even contemplate it.