The clustered regularly interspaced short palindromic repeats (CRISPR) cas9 system is an up-and-coming biological technique with the potential to revolutionise the medical landscape.

If it can be harnessed, it could potentially lead to tremendous advances in disease treatment. However, it also comes with a heavy burden of ethical concerns.

What is CRISPR?

Short palindromic repeats relates to a pattern of genetic code with short segments of DNA repeated next to each other (that is also read the same when reversed).

These repeats are interspaced, meaning that there is a small segment of spacer DNA between the repeated segments.

CRISPR in action

As viruses progress they invade cells to reproduce, eventually killing the cell. Certain viruses called bacteriophages invade and replicate within bacteria.

Scientists have made the discovery that the spacer DNA matches viral DNA, leading to the theory that bacteria use the CRISPR system to cut up viral DNA and incorporate it to protect against future infection.

The spacer segments are essentially the history of the viruses that have been neutralised.

Modifying genes to fight disease

Scientists now believe that this system can be exploited for medical benefit through genome editing to switch off DNA or modify genetic codes.

By inserting a segment of our own DNA (for example, the DNA for a genetic disease) into the CRISPR system, it can create proteins that hunt down the target DNA and inactivate it.

This gives scientists the potential to edit a person’s genes, and remove those that cause diseases such as cystic fibrosis and sickle cell anaemia.

Do the rewards outweigh the risks?

Such a system has the potential to revolutionise how we treat disease, with scientists suggesting it as a potential alternative to antibiotics for treating bacterial infections, including those superbugs resistant to antibiotics and for the treatment of cancer.

However, there is also concern in terms of the direction this type of science is headed.

Beyond destroying harmful gene sequences, new genetic sequences can be added to a DNA, leading to the possibility of outlandish, Hollywood-style experiments. The technology could potentially be used to try to recreate extinct animals or create genetically modified humans.

There is therefore a strong sense of caution tempering the optimism surrounding the promise of medical gene modification.