By Milo Moran
A Chinese scientist is making the controversial claim that he’s helped create the first gene-edited babies using the cutting-edge bio-technology CRISPR.
In 2015, Chinese researchers edited the genes of a human embryo using this method, but they only did it in a petri dish. There was a global outcry, and scientists from around the world pleaded for them not to do it again.
Now, He Jiankui from the Southern University of Science and Technology in China, claims that twin girls born earlier this month have DNA which he was involved in modifying. According to medical documents, the University has been recruiting couples for an experiment in which they used CRISPR to produce children resistant to HIV, cholera and smallpox. Crucially, the data shows that genetic tests have been carried out on 6-month-old foetuses.
CRISPR-Cas9 is the most accurate method of editing DNA we have at our disposal. It uses two molecules, unsurprisingly called CRISPR and Cas9. CRISPR perfectly replicates a section of DNA from a target cell, and uses it to guide Cas9 to the same site. Cas9 is like a molecular pair of scissors, which can recognise locations in a strand of DNA and cut it, allowing other genes to be added or removed. CRISPR is used by bacteria to fight off viral infections: when viruses attack they try to insert their own genes into a cell, but CRISPR-Cas9 allows bacteria to recognise the viral DNA strands and then cut them into harmless pieces.
CRISPR-Cas9 is a vast improvement on our previous methods of genetic engineering, which included irradiating plant seeds in the hope that they would develop useful mutations, and the “gene gun”, which fires a microscopic gold pellet into a cell, covered in DNA which the cell could potentially absorb and replicate.
Human gene editing could be used to remove genetic diseases such as Haemophilia, Cystic fibrosis, or Tay-Sachs disease. Indeed, the Chinese project in 2015 removed the genes for the fatal blood disease Thalassaemia from an embryo. However, many fear it will be take us down a slippery slope that leads to so-called “designer babies”: children designed to have desired traits like high IQ, physical fitness, and desired hair or eye colour. The idea that parents could tailor-make a child to their exact physical and behavioural specifications is an ethical minefield, and naturally people are worried.
There are also technical concerns, we do not know the extent of the health effects CRISPR could cause: editing one gene may have knock-on effects which have not been studied properly. Similarly, if a genetically modified human goes on to have children, could there be unforeseen consequences of them passing on altered genes.
The birth of the first GM Human would be a huge milestone in medicine, but in order to prevent the technology being misused, many scientists believe a major change in the law is necessary. Channa Jayasena of Imperial College London said, “We urgently need an international treaty to regulate gene editing of humans, so that we can decide if and when it is safe to use”.
In the UK, the law states that human embryos cannot be genetically modified for IVF, however they can be modified for some research, provided they are destroyed within a certain time window. Many other countries have banned the editing of human genes outright, although the use of genetic engineering on animals and plants in agriculture is widely accepted. China, by contrast, has one of the most unrestrictive policies of any nation, which has seen Chinese scientists leave Western countries and return to China to establish research programmes.