It took 20 years to complete 8% of the untested human genome, and the first 92% needed time to sort. This massive task mobilized hundreds of researchers from around the world under the auspices of the Federation Telomere-to-telomere (T2T), and published in six different scientific publications, all of which were published Science1Er April 2022 for a special issue on this topic.
Divide into long continuous series
Why was it so hard to deploy this little 8%? Because they are located in chromosomal regions known for their specific structure. The– The area at the end of the chromosome arm – and the centromere – in the center – are made up of long continuous series. As their name implies, these are regions A base (A, T, C or G) or a short sequence of bases is repeated a large number of times. Previously sequencing techniques could not handle these very long pieces of DNA, so-called Reads. To sort the DNA, you must first cut it into small pieces, then read the sequence and place each piece of DNA in the right place in the gene like a puzzle. Human genome project The first human genome was published in 2001, but some parts of the puzzle could not be reassembled.
T2T does not sift through a person’s DNA – a volunteer accepts his or her heritage.One note – but a human cell in culture; A Precisely. The mole is a Of : அ Fertilized without genetic material a . The resulting cell Two identical pairs of each chromosome (46 XX in 76% of cases and 46 XY in 25%). Despite this somewhat strange appearance, there is nothing to suggest that the mole of a mole is different from other cells, says Megan Dennis, a scientist at the University of California who is a member of T2T.
The last parts of the puzzle
Advances in technology have made it possible to read 3,054,815,472 basic pairs of chromosome DNA and an additional 16,569.A sequence that sends pieces of DNA to read through a membrane with only 1.5 small pores Diameter at their narrowest point. They were able to read Reads Of, Includes more than 100,000 basic pairs with the highest accuracy, and therefore the longest continuous series that have caused problems up to now. Sorting data generated Pacific Biology, Which has a specific sorting base for long queues. The scientists were able to place the final pieces in the large genetic puzzle they had assembled.. T2T scientists used this
Thanks to this, the human genome is enriched with nearly 200 million basic pairs – 90% of which are located in centromeres – from which scientists have identified 99 new, potentially coded genes and 2,000 other untested candidates. Errors in the old reference gene have also been corrected. This version of the human genome 2.0, T2T-CHM13, will certainly be at the heart of many genetic discoveries in the future.
Scientists have already identified genetic variations in the centromere region – whether these nuances contributediseases. Other areas now accessible may reveal the secrets of evolution Man. Structurally, the analysis of centromeric sequences, especially when nothing guides, may allow scientists to understand why centromere is formed here and nowhere else. In short, the range of possibilities seems endless.
Enrich the database
T2T does not stop its investigations here. The federation has already integrated Human Pangenom Reference Federation Aimed at sorting . ” Pangenomics is about capturing the diversity of the human population and ensuring that we hold the whole gene correctly. », Benedict Baden, co-editor Appeared Science.
Meanwhile, the T2T-CHM13 reference gene has been supplemented with 2001 (labeled GRCh38) and is available with full reference. , It is ready to be divided into all sorts by scientists all over the world.