2023-05-11 20:00:00
The reference genome of our species has been the backbone of human genomics since its first draft was published in 2021 in two of the most prestigious scientific journals in the United States, Nature y Science. Just two years later, in April 2003, the sequencing of the first complete human genome was announced.
The sequence, of 3,000 million DNA bases, called reference genome, was made up primarily of DNA donated by people from the city of Buffalo, New York. Until now, when doctors and researchers study an individual’s genome, they compare it to the reference genome to identify differences. But is it possible to compare all of humanity with a single genome? No, because a reference genome does not convey the genomic diversity of the human species.
How much do you know about DNA?
Now, however, a team of researchers led by the National Human Genome Research Institute –NHGRI– just published a new updated sequencing that offers a much more complex picture of human genetic diversity. The new reference to the “human pangenome” has been released this week in 3 articles published in the journal itself Nature, and includes the genomic sequences of 47 different individuals. The scientists, however, hope to increase that number to 350 by mid-2024.
A more complete picture of the human genetic essence
A genome is the DNA instruction set that helps every living thing develop and function. Genome sequences differ slightly between individuals. In the case of humans, the genomes of two people are, on average, more than 99% identical. But it is the small differences that contribute to each person’s uniqueness and can provide invaluable information about their health, helping to diagnose diseases, predict outcomes and guide medical treatments.
In the case of humans, the genomes of two people are, on average, more than 99% identical.
To understand these genomic differences, scientists create sequences of the reference human genome to use as standard: A digital fusion of human genome sequences that can be used as a comparison to align, assemble, and study other human genome sequences.
“Everybody has a unique genome, so using a single reference genomic sequence can lead to inequities in genomic analyses,” he says. Adam Phillippy, a researcher in the NHGRI Department of Computational Genomics and Statistics and co-author of the main study. “For example, predicting a genetic disease might not work as well for someone whose genome is most different from the reference genome,” he continues.
Gaps and ramifications
The current reference human genome sequence has gaps that reflect unavailable information, especially in areas that were repetitive and difficult to read. Recent technological advances, such as long read DNA sequencingwhich reads longer stretches of DNA at a time, helped researchers fill in those gaps to create the first complete sequence of the human genome.
Darryl Leja, NHGR
Differences between the penultimate and the current new version of the human pangenome
Furthermore, whereas the previous reference genome sequence was single and linear, the new pangenome represents multiple versions of the human genome sequence at the same time. This gives researchers a broader range of options for using the pangenome in the analysis of new sequences.
“By using the pangenome reference, we can more accurately identify larger genomic variants called structural variants,” he explains. Mobile Asri, a student at the University of California Santa Cruz and co-author of the article. “Now we can find variants that were not identified by previous methods.
“This new version of the human pangenome will allow us to represent tens of thousands of novel genomic variants in regions of the genome that were previously inaccessible,” adds the Yale University student and also co-author of the article, Wen-Wei Liao. “With it, by improving our understanding of the link between genes and disease, we hope to improve clinical research and make new advances in medicine reach many more people,” he concludes.
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