Future research on the technique may improve the accuracy and efficiency, however scientists still don't fully understand the role of the DNA, and all of its genes. Therefore it is impossible to assess the risks from mis-targeted changes in the DNA sequence, which would affect both the treated embryo and any future generations."
Prof Shirley Hodgson, Professor of Cancer Genetics, St George's University of London, said: "I think that this is a significant departure from currently accepted research practice. This is because any manipulation of the germline of human embryos is potentially heritable. Can we be certain that the embryos that the researchers were working on were indeed non-viable? In the past all the gene therapy research that has been approved by regulatory bodies has been somatic, not germline, because of the potentially unpredictable and heritable effects of germline research. The fact that these researchers found that there were a number of "off target" mutations resulting from the technique they used is clearly a worry in this context. Any proposal to do germline genetic manipulation should be very carefully considered by international regulatory bodies before it should be considered as a serious research prospect. This is because of the obvious concerns about the heritability of the genetic alterations induced, and the way in which such research could spread from work on "non-viable" embryos, to work on viable ones once this type of research had been accepted in principle by international regulatory bodies."
Prof Darren Griffin, Professor of Genetics, University of Kent, said: "Given the widespread use of the CRISPR/Cas9 system, such announcement was inevitable, sooner rather than later. We clearly have a lot of thinking to do. Germline manipulation is currently illegal in the UK but the question is bound to be asked whether this should change, especially if the safety concerns are allayed."
Associate Professor Peter Illingworth is Medical Director at IVFAustralia: "This is a fascinating piece of experimental science. Using abnormally-fertilised human embryos (I.e. With three sets of DNA instead of two), they have studied whether the a human gene can be modified. They have demonstrated that, in some embryos, but not all, they can change the abnormal human gene. They also find that other genes are affected which may be a serious concern. What they have shown is that it is technically possible, not that it is practically feasible or safe."
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