A new gene-editing breakthrough A FEW years ago, molecular biologists made a breakthrough. By borrowing an antiviral mechanism called CRISPR-Cas9 from bacteria, they created an easy way to tweak the genetic information in a cell nucleus. This has implications for medicine and agriculture. Unfortunately, a dispute over who invented what parts of the technique first has threatened to curtail this potential. 

But that may not matter, for CRISPR-Cas9 turns out not to be the only way bacteria protect themselves from the attentions of viruses. In the latest edition of Cell, a group of researchers led by Feng Zhang of the Broad Institute in Cambridge, Massachusetts (who is one of the parties to the patent dispute), have announced their discovery of another such mechanism. Indeed, first indications suggest it may be even better than CRISPR-Cas9.

Like it, this mechanism, CRISPR-Cpf1, could become a tool that can deal with intractable genetic illnesses such as Huntington, and degenerative conditions such as Alzheimer. It might also be used to produce new classes of antiviral treatment, and thus curb infectious disease. Plant and animal breeders may find it useful, too, for creating new strains of crops and livestock. Indeed, because, like CRISPR-Cas9, it does not involve taking genes from one organism and implanting them in another, it will not count as �transgenic�, a bugaboo of campaigners and customers alike.

CRISPR-Cas9 consists of a pair of enzymatic �scissors� (the Cas9) and a guide sequence of DNA (the CRISPR) that tells the scissors where to cut. The dispute over inventorship has caused some, though not all, potentially interested companies to give the technology a wide berth. Monsanto, a plant-breeding and agrochemicals firm, has gone on record as saying that it is reluctant to employ CRISPR-Cas9 widely until it understands the intellectual property concerned. Drug companies have also circled at a distance. CRISPR-Cpf1, which uses a different pair of scissors, may not suffer from these legal problems.

CRISPR-Cpf1 may be better than CRISPR-Cas9 in another way, too. Cpf1 is a smaller and simpler enzyme (known technically as an endonuclease) than Cas9. That means it will be easier to deliver to the cells whose genes need modifying.

CRISPR-Cpf1 discovery also raises the question of how many other endonuclease-based systems are out there in the world bacteria. Viral infection is a serious threat to these microbes, and the natural job of both CRISPR-Cas9 and CRISPR-Cpf1 is to recognise viral genes and chop them up before they can do harm. Conversely, viruses are constantly evolving to escape such systems� attention, meaning bacteria need to generate new ones. The chances are good, therefore, that CRISPR-Cas9 and CRISPR-Cpf1 are not alone. As Dr Zhang himself puts it, �I can�t even begin to count how many there may be. There really is great diversity that we as a scientific community should go out and explore.�

The tools to carry out that exploration now exist. CRISPR-Cpf1, for instance, was found not by scrutinising bacteria directly, but by searching a published database of bacterial genetic sequences for promising-looking bits of DNA. This yielded two species that contain the new mechanism. Further searches might be equally rewarding�and as more gene-editing systems are discovered, it will be harder to monopolise their use via the patent system.

Despite the optimism of those who think the new techniques may calm qualms about genetic engineering, people are bound to have ethical worries�especially when it comes to applying them to human embryos. Earlier this year, Chinese scientists used CRISPR-Cas9 on an embryo (albeit one that was unviable, and could not therefore have developed into a person). 

That provoked calls for a moratorium on this line of inquiry. On September 18th researchers in Britain applied for permission to edit genes in human embryos, as part of a study of human development. Such embryos would have to be left over from IVF treatment, and could be studied for no more than two weeks of development. Nor could they be implanted to create a pregnancy, or for any other clinical purpose. Movement in the research is halting. But the direction of travel is clear.