Genetic engineering is also called genetic modification or GM. It involves modifying the genome of an organism by introducing a gene from another organism to result in a desired characteristic.
How has genetic engineering worked until now, and what are the limitations?
Generally it uses what’s known as a bacterial vector. In simple terms, you take the stretch of DNA you want to insert into an organism – say, for example, the DNA that makes a carrot produce vitamin A. You insert it into a bacterium, usually agrobacterium tumefaciens, and you introduce that bacterium into the organism you want to modify, say a rice plant. The bacterium acts as a delivery mechanism, inserting that stretch of carrot DNA into the rice plant’s genome.
This is a proven and reliable technique. The trouble is that for the carrot DNA to have the effect you want, and no effects you don’t want, you have to insert it at exactly the right place in the rice plant’s genome – and there’s no way of controlling where the bacterium is going to land. It’s a bit like trying to edit a book by taking a passage from another book and pasting it in at random. You may have to do this procedure many times before you get the result you’re looking for.
Q: And what has changed?
There are new techniques that enable DNA to be edited much more precisely – more like editing a book using a word processor. Arguably the example currently generating most excitement is CRISPR-Cas9, essentially a molecule that can find a particular point in a genome and snip out or insert chunks of DNA in a precisely targeted way.
The CRISPR-Cas9 technique was not invented, it was discovered in nature – a microbe that evolved over billions of years. Broadly, when an organism is attacked by a virus, it works by grabbing some of that virus’s DNA and inserting it into its own genome, so that when the virus is encountered again, the organism remembers and is ready to fight it off. It was only in 2013 that scientists realized how CRISPR-Cas9 worked in nature and that it could be used as a tool, so many of the implications are still being explored.
CRISPR-Cas9 is not the only new technique making genetic engineering more precise. Another example goes by the name of ZFNs, and progress here is further forward – it is the basis of a technique to attack HIV that’s currently in phase 2 clinical trials. There is no guarantee yet that CRISPR-Cas9 will be suitable for use in human therapeutics. But researchers are excited by how easy it is to use.
Human genetic engineering relies heavily on science and technology. It was developed to help end the spread of diseases. With the advent of genetic engineering, scientists can now change the way genomes are constructed to terminate certain diseases that occur as a result of genetic mutation . Today gene...