While many researchers say that human germline engineering is probably inevitable, they also express concerns about its use, both from a technical and an ethical perspective. Nature Biotechnology contacted 50 researchers, asking them what they thought about the use of CRISPR-Cas9 for human germline engineering; 26 researchers replied to their queries.
Human germline engineering with a tool like CRISPR-Cas9 is "only ethically acceptable if it is safe," says the Francis Crick Institute's Robin Lovell-Badge.
And there are, other respondents note, technical stumbling blocks to overcome before the approach can be deemed safe. For instance, off-target effects remain a challenge, but so are unforeseen effects of editing of the target and genetic chimerism.
"[I]ntroducing an improving genome modification may not always be without attendant disadvantages," Anthony Perry from the University of Bath says. "For example, with heterozygous carriers of the HbS single-nucleotide polymorphism for sickle cell disease, you eliminate sickle cell disease, but increase the risk of contracting malaria."
Many of the respondents say that they believe germline engineering would be ethical under certain circumstances, such as when it would prevent severe disease, as the Broad Institute's Feng Zhang says, but not if used for enhancement like editing an APOE gene, as Lovell-Badge adds.
The respondents also mostly favor a discussion of the pros and cons of using germline editing.
"We favor a moratorium on genome editing research on human germ cells while the pros and cons of this technology application are discussed, a determination is made as to whether or not there are any good arguments in favor of moving forward, and if so, clear guidelines are established for specific cases in which germline genome editing could be used," Edward Lanphier from Sangamo Biosciences adds.