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Gene editing used to repair diseased genes in embryos

4:30pm Thursday 3rd August 2017 content supplied byNHS Choices

The researchers found no evidence of mutations induced by the technique, when they examined the cells in a variety of ways. However, they did find some evidence of gene deletions caused by DNA strands splicing (joining) themselves together without repairing the faulty gene.


How did the researchers interpret the results?

The researchers say they have demonstrated how human embryos "employ a different DNA damage repair system" to adult stem cells, which can be used to repair breaks in DNA made using the CRISPR-cas9 gene-editing technique.

They say that "targeted gene correction" could "potentially rescue a substantial portion of mutant human embryos", and increase the numbers available for transfer for couples using pre-implantation diagnosis during IVF treatment.

However, they caution that "despite remarkable targeting efficiency", CRISPR-cas9-treated embryos would not currently be suitable for transfer. "Genome editing approaches must be further optimised before clinical application" can be considered, they say.



Currently, genetically-inherited conditions like hypertrophic cardiomyopathy cannot be cured, only managed to reduce the risk of sudden cardiac death. For couples where one partner carries the mutated gene, the only option to avoid passing it onto their children is pre-implantation genetic diagnosis. This involves using IVF to create embryos, then testing a cell of the embryo to see whether it carries the healthy or mutated version of the gene. Embryos with healthy versions of the gene are then selected for implantation in the womb.

Problems arise if too few or none of the embryos have the correct version of the gene. The researchers suggest their technique could be used to increase the numbers of suitable embryos.

However, the research is still at an early stage and has not yet been shown to be safe or effective enough to be considered as a treatment.

The other major factor is ethics and the law. Some people worry that gene editing could lead to "designer babies," where couples use the tool to select attributes like hair colour, or even intelligence. At present, gene editing could not do this. Most of our characteristics, especially something as complex as intelligence, are not the result of one single, identifiable gene, so could not be selected in this way. And it's likely that, even if gene editing treatments became legally available, they would be restricted to medical conditions.

Designer babies aside, society needs to consider what is acceptable in terms of editing human genetic material in embryos. Some people think that this type of technique is "playing God" or is ethically unacceptable because it involves discarding embryos that carry faulty genes. Others think that it's rational to use the scientific techniques we have developed to eliminate causes of suffering, such as inherited diseases.

This research shows that the questions of how we want to legislate for this type of technique are becoming pressing. While the technology is not there yet, it is advancing quickly. This research shows just how close we are getting to making genetic editing of human embryos a reality.


"Deadly gene mutations removed from human embryos in landmark study," reports The Guardian. Researchers have used a gene-editing technique to repair faults in DNA that can cause an often-fatal heart condition.

Links to Headlines

Deadly gene mutations removed from human embryos in landmark study. The Guardian, August 2 2017

Human embryo editing breakthrough is a 'major advance' towards controversial treatments for babies. The Independent, August 2 2017

Scientists edit genes in human embryos to prevent inherited diseases. Sky News, August 2 2017

Ethical concerns over dawn of the designer baby: Campaigners warn breakthrough that removed faulty DNA could lead to creation of 'superior' children with genes modified to improve appearance or intelligence. Mail Online, August 3 2017

Human embryos edited to stop disease. BBC News, August 2 2017

Links to Science

Ma H, Marti-Gutierrez N, Park S, et al. Correction of a pathogenic gene mutation in human embryos. Nature. Published online August 2 2017

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