What is gene editing or genome editing as
it is also known, and how does it work?
Let's start by talking about genes. These
are sections of the long DNA molecules coiled
up inside each cell of every living thing
from micro-organisms and insects, to plants
and animals, including humans. Think of DNA
as the instruction manual for an organism;
in people, genes can influence characteristics
such as your height and the colour of your eyes.
 
DNA is inherited from our parents; we have
a combination of two sets of genes, one from
each parent, brought together to produce a
new set of instructions, and reshuffled in
each generation. But sometimes these instructions
carry errors, and these can create problems.
Faulty genes can cause serious illnesses.
Humanity has a long history of figuring out
ways to modify genes. We have been cross breeding
plants to make them better to eat for thousands
of years. But with gene editing, we've made
a great leap forward. This increasingly accurate
new technology is faster to use, relatively
simple and cheap compared with previous methods,
and promises huge benefits.
In a nutshell, it works by identifying then
cutting pieces of DNA. One way of doing this
uses a component known as CRISPR to pinpoint
the precise DNA sequence within the gene to be altered.
Then an enzyme called Cas9 snips
through the DNA, changing it or allowing it
to be replaced by another stretch of DNA that
is introduced at the same time. This can either
replace a faulty gene with a healthy one,
or change a gene to make it behave differently.
The methods act like a find-and-replace for
the genetic instruction manual.
By making these microscopic changes to DNA,
gene editing has the potential to make
big changes to our lives.
Gene editing is already transforming genetic research.
But at this early stage of such a powerful
technology, it's crucial that we weigh the
potential benefits against the possible negatives.
First, let's look at the positives.
Gene editing could make radical improvements
to human health. For example, in 2015 doctors
used genome editing techniques to cure a baby
girl's leukaemia. In the future, we may
be able to fix the gene mutations that predispose
some people to cancer, or enable new therapies for HIV, or edit the genes that cause hereditary diseases.
In the plant world, it could make crops more
nutritious, disease-resistant, and able to
grow in difficult conditions.
By editing animals' genes, we could help them
resist diseases. Scientists are currently
working to edit the genes of mosquitos, to
prevent them from carrying malaria.
So genome editing has enormous positive potential.
But what about possible downsides?
Genes could be edited in early human embryos
to alter characteristics such as eye colour,
that have no bearing on health. This raises
the possibility of 'designer babies', and
changing an embryo's DNA would affect not
only the child, but their descendants too.
These same techniques could also be used to
create designer pets, or develop more virulent
microbial diseases.
So alongside the many benefits of genome editing,
there are also some ethical and societal concerns
to consider. The technology is already in
our hands. Now's the time to debate how we
use it, regulate it, avoid negative uses and
unlock its potential to provide life-changing
solutions to some of the world's biggest challenges.
