This is a triumph of basic science with huge implications. Crispr technique breaks the mould

When I saw it working in my lab my jaw dropped

Craig Mello
Wednesday 06 November 2013 22:29 GMT

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Louise Thomas

Louise Thomas


There are occasions in science when something comes along that breaks the mould. A decade or so ago, in my field of research, it was a technique called RNA interference, a highly effective way of turning down the activity of genes, rather like the dimmer switch of a light.

In the past year, something equally amazing has come along and, in many ways, it is even better than RNA interference. This discovery, known by the acronym Crispr, can permanently alter the genome of essentially any organism with extreme precision and high efficiency.

This is a triumph of basic science, a tremendous breakthrough with huge implications for the science of molecular biology and molecular genetics. Crispr enables us to get incredibly efficient targeting of the genes that we wish to mutate and we can induce these changes in both “alleles”, the two copies of each gene that we inherit from our mothers and fathers.

We can do that by directing the editing “scissors” – a DNA-cutting enzyme called a nuclease – to any part of the genome simply by changing the sequence of the RNA guiding molecule we attach to it.

It’s one of those things that you have to see to believe. I initially read the scientific papers on Crispr like everyone else, but when I saw it working in my lab my jaw dropped. A total novice in my lab got it to work.

There are obvious applications in medicine, but in a laboratory setting this is absolutely transformational. You can move so much more rapidly in understanding gene function and so should accelerate the pace of research. But the wider applications are tremendous. Crispr is absolutely huge. It’s incredibly powerful and it has many applications, from agriculture to potential gene therapy in humans.

But in terms of germline gene therapy on human IVF embryos, I would caution against it, certainly for any time in the near future. There are still potential “off-target” effects that could lead to unintended consequences. The safety issue has to be weighed against the medical need and here you are talking about the medical need of an unborn individual.

However, having said that, Crispr does lower the barrier to germline gene therapy tremendously. It’s much easier now to engineer a DNA molecule of an embryo.

I wouldn’t be surprised if someone at some time does suggest using Crispr on human IVF embryos because the technology is so easy to do. But I certainly think this kind of germline gene therapy should continue to be banned for the foreseeable future. There are so many other great ways to use Crispr for the common good.

Professor Craig Mello, of the University of Massachusetts Medical School, shared the 2006 Nobel Prize for physiology or medicine for the joint discovery of RNA interference.

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