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3.
 
CRISPR went unnoticed by biologists for decades. It was only at the tail end of the 
1980s that researchers studying Escherichia coli noticed that there were some odd 
repetitive sequences at the end of one of the bacterial genes. Later, these sequences 
would be named Clustered Regularly Interspaced Short Palindromic Repeats - 
CRISPRs. For several years the significance of these CRISPRs was a mystery, even 

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when researchers noticed that they were always separated from one another by 
equally odd 'spacer' gene sequences. 
4.
 
Then, a little over a decade ago, scientists made an important discovery. Those 
'spacer' sequences look odd because they aren't bacterial in origin. Many are actually 
snippets of DNA from viruses that are known to attack bacteria. In 2005, three 
research groups independently reached the same conclusion: CRISPR and its 
associated genetic sequences were acting as a bacterial immune system. In simple 
terms, this is how it works. A bacterial cell generates special proteins from genes 
associated with the CRISPR repeats (these are called CRISPR associated - Cas - 
proteins). If a virus invades the cell, these Cas proteins bind to the viral DNA and help 
cut out a chunk. Then, that chunk of viral DNA gets carried back to the bacterial cell's 
genome where it is inserted - becoming a spacer. From now on, the bacterial cell can 
use the spacer to recognise that particular virus and attack it more effectively. 
5.
 
These findings were a revelation. Geneticists quickly realised that the CRISPR system 
effectively involves microbes deliberately editing their own genomes - suggesting the 
system could form the basis of a brand new type of genetic engineering technology. 
They worked out the mechanics of the CRISPR system and got it working in their lab 
experiments. It was a breakthrough that paved the way for this week's 
announcement by the HFEA. Exactly who took the key steps to turn CRISPR into a 
useful genetic tool is, however, the subject of a huge controversy. Perhaps that's 
inevitable - credit for developing CRISPR gene editing will probably guarantee both 
scientific fame and financial wealth.