How CRISPR, the "genetic scissors" that promised a revolution in medicine, was found by pure chance – BBC News

In 2003, an international group of scientists unveiled our genetic map and published the full sequence of the human genome.

That description of the DNA chain in the 23 pairs of chromosomes in the nucleus of every human cell ushered in a new era for medicine: the genetic age.

The next big step was in 2012, when a way to change that DNA sequence was discovered, by adjusting the genetic instructions of life.

It was achieved by one genetic processing technique known as CRISPR / Cas9.

The simplest way to understand CRISPR is to propose genetic scissors that can cut part of the DNA.

Many call it "cut and paste" technique because it makes it possible to change a DNA chain: by eliminating a part, the chain is reconstructed and forms a new series.

This procedure is a revolution in science because enables us to rewrite our genes and could lead to the treatment of previously untreatable hereditary diseases.

This huge scientific milestone it came from pure chance.

Scientific curiosity

After the publication of the human genome, several countries and private companies have spent millions of dollars to understand how this genetic sequence can be changed, but the discovery of the famous CRISPR scissors did not come as a result of that investment.

Jennifer Doudna at the University of California, Berkeley
Jennifer Doudna, from the University of California, Berkeley, discovered the CRISPR mechanism.

"It was an exciting example of how fundamental research can lead to unexpected and interesting paths," Professor Jennifer Doudna of the University of California, Berkeley, told the BBC.

Doudna is one of the most important people involved in the discovery of CRISPR.

"For me it was a convergence between the science inspired by curiosity and this growing field of genetic engineering, "said the expert.

Doudner and his team were not looking for a way to adjust genetic structures. They studied something completely different: they wanted to know how bacterial immunity works.

To do this they analyzed cells from bacteria, specifically something in these cells called CRISPR sequences: patterns of repetitive sequences containing sections of virus DNA.

In fact, the name CRISPR comes from the abbreviations in English of the name of this type of sequences: short palindrome repeats spaced apart and grouped together.

It was discovered that these sequences were the way the bacteria were "vaccinated" against viral infections.

"It is a genetic reminder of viral information that bacteria use as an adaptive immune system, as a way to defend against infections," explains Doudner.

The scientist wanted to understand the mechanism more thoroughly.

Doudner and his team examined the bacteria when they reached the milestone that would radically change genetic biology.

"I thought studying how bacteria can program enzymes to find and destroy viruses was fascinating in relation to the evolution of an immune system in microbes," he said.

Enzymatic scissors

But while studying how this enzymatic scissors works that the bacteria used to cut off defective DNA and thus defend itself against viral infections, Doudner and his colleague Martin Jinek had a "Eureka moment".

They realized that this enzyme CRISPR / Cas9 can be programmed to cut DNA sequences very precisely.

It was one of the most important discoveries in the history of biology because it opened the door to genetic engineering and the ability to rewrite the genome not only of humans, but of every living organism.

"CRISPR can treat, cut and replace a damaged DNA sequence with a healthy version," explains Dr. Rodolphe Barrangou from North Carolina State University, who also studied this technique.

Scientists have managed to use this mechanism correct some genetic diseases in mice, but there is still a lot to explore.

Not everything is rosy: a new study published last July warned of the dangers of this form of genetic processing, which often causes unwanted mutations.

There are also many who fear that this technique could be used in a dubious way, for example to create "design baby & # 39; s".

DNA modification illustration
Some are afraid of genetic manipulation, others believe it can be our salvation.

On the other hand, CRISPR has lost a bit of its status in recent years: new methods have been developed to adapt the genome, such as the so-called basic processing system.

Explore freely

But the truth is that understanding and controlling the mechanism of CRISPR / Cas9 was marked before and after in genetic biology.

And Doudner is of the opinion that this finding emphasizes the importance of free, non-specific research.

"I think this is a great example of scientists who wanted to solve an unknown work because it was interesting for them and not because they expected to make it a technology," he told the BBC.

For his part, Barrangou believes that this is a good lesson for the future

"I think this is a reminder that scientists should have a certain amount of freedom," he said.

"Science is not a linear discipline, there is no straight path from where things start where they end and I think CRISPR is a very good example of how science works."


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