Record-breaking sequencing lifts the veil on unknown regions of the human genome

Record-breaking sequencing lifts the veil on unknown regions of the human genome

Our knowledge of the human genome has just had its most significant advance since it was first sequenced in 2003.

In 2003, research was changed forever by the very first sequencing of the human genome. A resounding scientific feat, and the culmination of a long series of founding works… or almost. Because despite everything, our genetic heritage still has gray areas; but a team of researchers has just put a spotlight on these to produce what they describe as “the first truly complete, gap-free sequencing of the human genome”.

In this work published in the prestigious journal Science, the researchers describe a process that allowed them to cover the entire genome from end to end, from the first to the last chromosome, and without leaving the slightest molecule to chance. But how did the researchers find out if the genome had already been sequenced before?

Shadow areas now clearly visible

The answer lies in genomics, a sub-discipline of biology that offers a more comprehensive approach than genetics. The latter studies the function, composition and heredity of genes, those DNA sequences that define every aspect of our being.

But since 2003, science has come a long way; since 2003, progress in research has shown that the functioning of genes is much finer and more complex than previously thought. We now know that our genome is not just a simple succession of individual genes. It is more than the sum of its parts, and all the elements are intrinsically interdependent.

For the many researchers who participated in establishing this observation, there was therefore only one possible conclusion: the researchers of the Human Genome Project had necessarily missed something. Until today, the scientific community estimated that approximately 8% of the genome remained unexplored due to a lack of adequate techniques.

This work will weigh heavily in fundamental research, but also in clinical medicine. © National Cancer Institute

A “new pair of glasses” for research

But it took until our time for sequencing techniques to progress, and finally become complete and precise enough to spot a needle in this huge biochemical haystack. The Herculean efforts of researchers at the University of California have thus made it possible to identify 200 million additional A, T, G or C base pairs distributed in nearly 2000 potential new genes.

It is a small revolution in itself, since our knowledge of the human genome has direct implications in all aspects of medicine. It is safe to say that this work will inevitably improve our understanding of evolution and human health.

“It’s like putting on a new pair of glasses,” says Adam Philippy, a bioinformatician affiliated with the Human Genome Project research institute. “Now that we can see everything in detail, we’re getting closer and closer to understanding how it all works!” he enthuses.

A treasure chest full of missing pieces of the genetic puzzle

The other particularly interesting aspect is directly related to where they discovered that famous missing 8%. Most of the material was located in two very specific regions of the chromosomes: the centromeres (the center of the “cross” that a chromosome forms during cell division), and the telomeres.

We can very summarily assimilate the latter to caps that cover and protect the ends of the chromosomes. These are no more and no less than cleverly folded balls of DNA, and the telomeres therefore prevent them from unraveling, much like the consolidated end of a shoelace.

The fact of having been able to completely sequence these regions will probably change many things in the study of our genetic heritage. Indeed, there are many particularly important genetic and physiological phenomena whose keys are probably hidden in these parts of the chromosomes.

For example, numerous works suggest that several keys to the mechanisms of aging are hidden in the telomeres. One day, new elements could therefore contribute to producing treatments aimed at slowing down or even reversing aging, as Jeff Bezos wishes.

But the most interesting thing is that it may be an additional fresh start. By exploring the new genetic regions mapped in this way, researchers could well identify other fundamental mechanisms, essential in the mechanics of the genome, and therefore new elements to explore.

If necessary, this would once again make it possible to resume all this work with a new perspective, a bit like researchers did when genomics first appeared, with potential new advances at stake.

The text of the study is available here.

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