The technique itself is both simple and elegant. That’s because CRISPR, which stands for ‘Clustered Regularly Interspaced Short Palindromic Repeat’, imitates the immune mechanism of bacteria when attacked by a virus in nature. Confronted with such a situation, the bacteria will take strips of the virus’s DNA and insert it into their own using an enzyme called Cas. These newly formed sequences are the CRISPR, which the bacteria then uses to produce RNA copies to recognise viral DNA and repel future attacks.
While these processes have been observed and understood since the early 1990s, it wasn’t until 2013 that CRISPR was transformed into a tool suitable for gene-editing. That was achieved by replacing the bacterial CRISPR RNA system with a modified guide RNA which now acted as a signal to inform an enzyme, called Cas9, where to look. This allowed the enzyme to efectively scan a cell’s genome to isolate a match before slicing it out. Applying this same process, scientists can change or add DNA within a cell in a manner reminiscent of cut, copy and paste – although, for now, a slight margin of error remains. Decades after confirming DNA is responsible for genetic inheritance, and more than sixty years since the invention of the silicon transistor, information technology can reprogram biological systems with increasing ease.
Already, governments in a number of countries including the US and UK have approved the use of CRISPR-Cas9 in human embryos and adults. You can even buy home kits online using the same system to modify bacteria in your spare time. Altering bacteria to glow in the dark like jellyfish or develop resistance to certain strains of antibiotics might have won a Nobel Prize thirty years ago – today children in middle school are doing it.
Editing Destiny
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