This breakthrough is the subject of six articles published in the journal Science (new window) and a handful of others in peer-reviewed journals.
The announcement comes almost 20 years after the announcement of the completion of the first draft of the human genome on April 14, 2003.
Back then, the Human Genome Project was the culmination of a decade of work involving dozens of scientists from six countries with a budget of around $3 billion. This made it possible to map around 92% of the genome.
landmarks
- A person’s genome contains all of their genetic material, which is carried by the DNA found on the 23 pairs of chromosomes inherited from their biological parents.
- It’s like a 23-chapter instruction book that articulates the ins and outs of a person and allows their body to function properly.
- Genetic material is present in every human cell. The nucleus of every human cell contains between 20,000 and 25,000 sets (genes) and more than 6 billion letters (these are the letters A, C, G and T).
- Every cell reads the genes that affect it. For example, a skin cell reads information about the texture of the skin and the amount of hair, but not instructions about the eyes or the heart.
The remaining 8%
The sequencing announced Thursday corresponds to the 8% remaining to be mapped. It completes the work announced in 2003, but also all the research efforts carried out over the past two decades that have benefited from new decoding techniques that have made the sequencing work much less tedious and much more precise.
This percentage mainly corresponds to “holes” in the sequences, which are due to the technology of the time not being able to complete the puzzle at more difficult parts of the chromosomes, which contain areas with DNA sequence repeats, says Stéphanie Lord-Fontaine, vice-president for scientific affairs at Génome Québec.
New technologies have allowed researchers to get the genome close to the centromere, the middle of the chromosome, and into the telomeres at the end of the chromosome, notes Stéphanie Lord-Fontaine.
All of these technological breakthroughs have also improved sequencing on a much more practical level. Sequencing an entire human genome costs $1,000 today and can take a few days, she explains.
When we have the complete telomere-to-telomere sequence, we can see the regions that correspond to the “dark matter” of the genome that remained hidden. These regions harbor complex DNA variations that hold clues to diseases we’ve been searching for but haven’t found answers to yet, T2T co-chair Adam Phillippy gushed during a press conference to mark the announcement.
In particular, the ability to read larger portions of DNA sequences has uncovered more than 2 million additional mutations in the human genome.
“We thought that there was no relevant information in these areas, but they are actually linked to about 600 genes that would be medically relevant. »
— A quote from Stéphanie Lord-Fontaine
One of the researchers involved in the work brings the literature comparison back to life. In life’s great manuscript, we have access to chapters that have never been read before, said Evan Eichler, a physician at the University of California, Santa Cruz.
A new reference sequence coming soon
The work done since the first draft has created a reference sequence of the human genome used by geneticists around the world.
For example, this international standard has led to several discoveries, particularly in understanding rare diseases. Since then it has been updated a few times.
We can now diagnose thousands of rare diseases caused by genetic mutations. In the case of cancer, we know that we can predict the response to treatment based on the mutations present in patients’ tumors, says Stéphanie Lord-Fontaine.
“We know much better about hereditary cancers like breast cancer caused by BRCA gene mutations. We are even able to sequence tumors and predict the drugs that will be effective against specific mutations. »
— A quote from Stéphanie Lord-Fontaine
Personalized medicine will be increasingly present in clinical practice in the coming decades.
Photo: metamorworks
The revolution goes on
In light of this announcement, the GRCh38 reference genome used since 2019 is obsolete and will be replaced with a new version based on the finished version.
Several research teams have already started using a preliminary version of the full human genome sequence in their research.
This sequence has already led to a better understanding of genomic biology, and I look forward to discoveries in these newly discovered regions over the next decade,” said Dr. Karen Miga, also co-chair of the T2T consortium.
The new version will be particularly valuable for studying the full variation of the human genome, ie the differences between individuals’ DNAs. It will also allow to continue and refine the work started with the previous versions in the field of personalized medicine.
In the not too distant future, the sequencing of a person’s genome could provide their genetic portrait and be used in routine clinical care. His doctor will be able to adjust his medical procedures according to his information.
Being able to choose the right drug for the right patient at the right time; Predicting the genetic risks of diseases; Predicting the response to specific drugs in terms of patient metabolism. There is a wide range of uses to consider, says Ms Lord-Fontaine.
Ms. Lord is also pleased with the inclusion of personalized medicine and the presence of the term genomics in the plan presented by Christian Dubé, Quebec Minister of Health and Social Services, to implement the necessary changes in healthcare. The word genomics appears on page 69. This is a first! It’s coming, don’t give up.
Towards a Quebec reference genome
Génome Québec is currently working on creating a Québec reference genome. We have started sequencing a cohort of 2,000 participants as part of the CARTaGENE project, says Ms. Lord-Fontaine.
CARTaGENE is a public research platform consisting of both biological samples and health and lifestyle data from 43,000 Quebecers aged 40 to 69.
The goal is to create a Quebec reference genome that will contain a catalog of genetic variations that will be very useful for interpreting the different mutations present in the population.
A genome is very complex. Clinicians need a reference genome for a given population to get accurate mapping. We can use this map when diagnosing patients, concludes Stéphanie Lord-Fontaine.