杏吧原创

A handful of protesters were leafleting people arriving for a conference on creating gene-edited children in London last week. The Stop Designer Babies campaign group claimed in a press release that those at the meeting 鈥渁re planning how to conduct GM baby experiments without asking the public鈥�.

It is true that this meeting was about coming up with guidelines for how to conduct the first clinical trials of human germline genome editing, making changes that could pass down the generations. But those involved want to consult the public, and many think the guidelines will deter rather than encourage further attempts, at least in the short term.

If people have to tick off a checklist聽before trials begin, they aren鈥檛 going to get far down the list, says Andy Greenfield at the MRC Harwell Institute in the UK.

This meeting was a direct result of聽the announcement last November that a woman in China had given birth to two genetically edited baby girls. This led to the establishment of the International Commission on the Clinical Use of Human Germline Genome Editing, a group of doctors, biologists and ethicists tasked with considering the potential uses of聽the聽technology and drawing up guidelines for how to proceed.

For now, the consensus remains that . This is because, at the group鈥檚 last week, two broad messages became clear. First, we still don鈥檛 know if any of the many variants of CRISPR gene editing are safe enough to use for editing embryos.

Kathy Niakan at the Francis Crick Institute in London, who is using CRISPR to study early development, said her team is finding that the technique deletes large chunks of DNA in about 20 per cent of embryos. This was discovered only recently. Effectively, biologists were looking for聽spelling mistakes and not noticing that whole pages were missing.

Meanwhile, Hui Yang at the Chinese Academy of Sciences has been trying a more precise form of CRISPR, called base editing, in animal and human embryos. His team has found unintended changes too. Yang聽hopes a new method called prime editing might work better.

The second message is that many attendees see no pressing need to resort聽to editing the genomes of human embryos. Almost all serious genetic diseases can be prevented by聽screening the genomes of IVF embryos before implanting them in聽a聽uterus, said Frances Flinter at聽Guy鈥檚聽and St Thomas鈥� NHS Foundation Trust in London. This is known as pre-implantation genetic diagnosis (PGD). Cases where genome editing would be the only way for people to聽have healthy children are 鈥渋ncredibly rare鈥�, she said.

When PGD fails, it is usually for reasons such as it not being possible to extract eggs, or the embryos failing to develop. Gene editing won鈥檛 solve these problems, said Peter Braude of King鈥檚 College London.

Where PGD falls down is if you want to select out more than one mutation at a time. Some think germline genome editing could be used to correct multiple mutations at once, but Braude is sceptical. 鈥淭hat鈥檚 PR, not science,鈥� he told New 杏吧原创.

Adam Pearson, a broadcast journalist born with a condition called neurofibromatosis, questioned the assumption that genetic disorders are always faults to be eliminated. However, he then went on to suggest that he and his wife might use PGD to ensure that their children didn鈥檛 inherit neurofibromatosis.

Several attendees questioned the聽focus on genome editing when聽many families have yet to get access to existing, safer technologies for preventing genetic disorders. Nick聽Meade at Genetic Alliance, which聽supports people with genetic conditions, said not all people in the聽UK who want PGD can get it.

Germline genome editing can鈥檛 solve any pressing medical need yet, but that may change. It is likely that we will one day be able to generate eggs or sperm cells from adult cells, said Azim Surani at the University of Cambridge. That would allow a wider range of uses, such as treating male infertility caused by mutations that stop sperm being produced.