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Chinese scientists edit genes of human embryos

27 April 2015

By Ayala Ochert

Appeared in BioNews 799

Chinese scientists report the first-ever genetic modification of human embryos using the CRISPR/Cas9 gene-editing technique, confirming rumours that these highly controversial experiments were underway.

Although the technique has been used extensively in adult human cells and animal embryos, this is the first time the CRISPR/Cas9 system has been used to alter the genes of human embryos. It was used to take out a faulty gene that causes the inherited blood disorder beta-thalassaemia and replace it with a working version of the gene.

Last month, scientists writing in the journals Nature and Science called for an international moratorium on the use of this so-called 'germline modification' of humans - in which all the cells, including sperm and eggs - are altered (see BioNews 795). They fear that any unintended effects of the technique would be passed down through the generations and leave an indelible mark on the human gene pool. There are also concerns that the practice could lead to 'designer babies' with genes for traits such as intelligence, athletic ability, or even hair and eye colour.

'This news emphasises the need for an immediate global ban on the creation of GM designer babies,' Dr David King, director of Human Genetics Alert, told The Telegraph. 'It is critical that we avoid a eugenic future in which the rich can buy themselves a baby with built-in genetic advantages.'

The research was led by Dr Junjiu Huang of Sun Yat-sen University in Guangzhou, who published the research in the online journal Protein and Cell. Huang told Nature News that the paper had been rejected by both Nature and Science because of ethical concerns. Huang and his team used non-viable human embryos that had been fertilised by two sperm, which ensured that they would only go through the first few stages of embryo development and would never result in live births.

They applied the technique to 86 embryos and left them for 48 hours to grow into eight-celled embryos. Of these, 71 survived and 54 of these were genetically tested. Only 28 contained the healthy version of the gene but only in some of their cells. Because of this low success rate, Huang said his team discontinued their research. 'If you want to do it in normal embryos, you need to be close to 100 percent. That's why we stopped. We still think it's too immature.'

More significantly, there were a surprising number of 'off-target' mutations in which the versions of the inserted gene appeared in parts of the genome where they shouldn't. This is one of the principal concerns of the use of the gene-editing technique in human embryos. The rate of these mutations was much higher than those seen in CRISPR/Cas9 studies involving adult cells or mouse embryos.

Despite calls to end experiments involving genetic modification of human embryos, it is thought that this is taking place in at least four labs in China. And one US genetics laboratory, on condition of anonymity, told MIT Technology Review that it too was using the gene-editing technique on human embryos rejected by IVF clinics.

The Telegraph | 23 April 2015
The New York Times | 23 April 2015
Nature | 22 April 2015
MIT Technology Review | 22 April 2015
Protein & Cell | 18 April 2015


02 October 2017 - by Dr Rachel Brown 
A genome editing technique called 'base editing' has been used to correct the mutation causing the inherited blood disorder beta-thalassemia in human embryos...
25 September 2017 - by Paul Waldron 
UK scientists have successfully edited the genome of human embryos to study the role of a gene key to the earliest stages of development...
31 July 2017 - by Charlotte Spicer 
Scientists in the US may have successfully used genome editing in human embryos to correct disease mutations, according to a report by MIT Technology Review...
27 March 2017 - by Emma Laycock 
Radiolab explores the science, the uses and the ethics of CRISPR in this podcast that was two years in the making...
13 March 2017 - by Dr Katie Howe 
Chinese scientists have successfully used genome editing to correct mutations in viable human embryos for the first time...

23 March 2015 - by Meghna Kataria 
Scientists have called for a worldwide moratorium on the use of the gene-editing technique CRISPR/Cas9 in human embryos and germ cells...
02 February 2015 - by Claire Downes 
AstraZeneca has joined up with academic and industrial research partners to use CRISPR, a new and much-hyped gene-editing technology in their quest for new medicines....
24 November 2014 - by Dr Paul Knoepfler 
Experimental mitochondrial replacement technology has a noble goal, but in my opinion there are too many unanswered questions and risks that remain to allow it to proceed at this time. I believe that moving forward with it would most likely be a tragic mistake for the UK...
28 July 2014 - by Dr James Heather 
Research has shown that it may be possible to 'cut' the viral DNA out of cells infected by HIV using genetic editing techniques, removing its ability to replicate...

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