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Human Clinical Embryology and Assisted Conception MSc


First genome editing of normal human embryos

13 March 2017

By Dr Katie Howe

Appeared in BioNews 892

Chinese scientists have successfully used genome editing to correct mutations in viable human embryos for the first time.

The study used CRISPR technology, which has previously been used to edit genes in non-viable human embryos (see BioNews 799  and 846). These attempts had very low success rates but it was not known if this was because the embryos had an extra set of chromosomes.

'[This study] does look more promising than previous papers,' Dr Fredrik Lanner of the Karolinska Institute in Sweden told New Scientist. Dr Lanner's team is also using CRISPR to edit genes in human embryos.

The team, led by Jianqiao Liu at the Third Affiliated Hospital of Guangzhou Medical University, used eggs leftover from IVF procedures and fertilised them with donor sperm from two men to create six embryos. One of the sperm donors had a mutation called β41-42, which causes beta-thalassemia, while the other donor had a mutation in the G6PD gene. This is a common cause of favism – a disorder in which eating foods like broad beans can trigger the destruction of red blood cells.

Two of the resulting embryos had mutations in the G6PD gene, and four embryos had the β41-42 mutation. The researchers injected them with the CRISPR machinery and allowed them to develop for two days. They then analysed the embryos' DNA to check whether the mutations had been successfully corrected.

The mutation in the G6PD gene was successfully repaired in one embryo. In the other embryo, it was corrected only in some cells, forming a mosaic embryo.

The β41-42 mutation was also only partially corrected in one embryo, forming another mosaic. CRISPR induced another mutation in another embryo, and the technique did not work at all in the two remaining embryos.

Speaking to New Scientist, Professor Robin Lovell-Badge of the Francis Crick Institute described the results as 'encouraging'. However, he warned that the numbers are far too low to make strong conclusions.

Before the technology could be used in the clinic, researchers would need to find a way to prevent mosaic embryos, for example by editing genes in sperm and eggs before IVF, rather than editing embryos.

There are also many ethical concerns over the use of genome-editing technologies. A recent report by the US National Academy of Sciences (see BioNews 889) advised that genome editing should be be restricted to genes that are known to cause or predispose people to serious conditions, and should only be carried out the absence of other alternatives – for example when none of a couple's embryos will be free of inherited disease.

The research was published in the journal Molecular Genetics and Genomics.

Molecular Genetics and Genomics | 01 March 2017
New Scientist | 09 March 2017


03 April 2017 - by Jennifer Willows 
The European Patent Office has declared that it intends to grant a broad patent for the use of CRISPR technologies to the University of California, the University of Vienna and Dr Emmanuelle Charpentier of the Max-Planck Institute in Berlin...

21 November 2016 - by Anneesa Amjad 
Chinese scientists have injected CRISPR/Cas9 gene-edited cells into a human for the first time...
26 September 2016 - by Anneesa Amjad 
A scientist in Sweden has become the first to edit genes in healthy human embryos...
11 April 2016 - by Ayala Ochert 
A second team in China report that they have created genetically modified human embryos, in an attempt to make them resistant to HIV, using the genome-editing technique CRISPR/Cas9...
01 February 2016 - by Ayala Ochert 
The Human Fertilisation and Embryology Authority has granted the first licence to a UK researcher to edit the genomes of human embryos...
27 April 2015 - by Ayala Ochert 
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...

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