Making the cut: Will this mean Ctrl+X for disease and Ctrl+V for talent?

John Parrington in Aeon:

Header_NationalGeographic_1212974Imagine if living things were as easy to modify as computer software. In such a world, farm animals or plants could be engineered to produce leaner meat or juicier fruit, or to withstand extremes of climate. Medical research would be transformed: we could generate mutant animals to model human disease, or engineer plants to be a source of new drug molecules. In fact, medicine itself would look very different. Instead of suffering the terrible effects of genetic diseases such as cystic fibrosis or muscular dystrophy, clinicians could just eliminate the defects from affected cells. But why stop there? Such conditions themselves could become a thing of the past. IVF embryos might be screened for genetic defects and corrected, before being implanted into the womb. Such a vision might either excite or horrify, depending on your point of view. But if all this sounds like science fiction, it’s time to talk about the new technology of gene editing. As the Nobel laureate Craig Mello, of the University of Massachusetts, recently told me: ‘There truly is a revolution in genetics going on right now.’

…What has changed? In a word, we now have a specific new form of genetic engineering, called gene editing. It’s highly precise, very efficient, and far easier to use than previous methods. Most importantly, it can be applied to practically any cell type, including a fertilised egg. This means it’s possible to create genetically modified plants or animals of practically any species, as well as to modify the cells of adult organisms, including humans.

Let’s compare this situation with the earlier state of the art. Gene editing uses a type of ‘molecular scissors’ – basically a protein that cuts DNA in two. Previous versions of such scissors cut the genome in multiple places, which had a tendency to cause havoc in a living cell. However, they could be used to cut DNA in a test tube, allowing genetic engineers to create gene constructs that could be introduced into a cell on a petri dish, or even a living animal such as a mouse. But the method of introduction was pretty haphazard. The edited scrap of DNA would be injected into the cell, and then one would just have to keep one’s fingers crossed for it to integrate itself with the genome at some useful location. It was a bit like using a cannon to perform organ transplants.

The scissors make a single snip, and then one’s chosen chunk of DNA is slotted neatly into place

There’s a reason I mentioned mice in the previous paragraph, and a reason why mice have been used so pervasively in genetic engineering projects for the past couple of decades. The reason is this: stem cells isolated from a mouse embryo can be genetically modified in culture and used to make a new animal.

More here.