Breaking news: Scientists decode first complete sequence human genome! Read how the new "seamless" map of the human genome reveals hidden regions important for understanding genetic diseases.
21 years ago, science managed to map about 92% of the human genome, which meant a revolution in biology and medicine, but what happened to the remaining 8%?
Now, a scientific team has managed to scrutinize it, thus achieving the first complete sequence of a human genome.
The new "seamless" map of our DNA reveals hidden regions important for understanding genetic diseases, reproduction, human diversity and even the evolution of our species.
Actually, completing the human genome sequence has been like putting on new glasses," summarizes researcher Adam Phillippy.
Scientists decode first complete sequence human genome
Behind this scientific milestone is the T2T (Telomere to Telomere) Consortium, with more than a hundred researchers led by Phillippy, from the National Human Genome Research Institute (NHGRI).
Also, Karen Miga, from the University of California-Santa Cruz, in the USA.
The description of these missing pieces was first published in May 2021 in the bioRxiv repository - without the review of other researchers.
Now it is when it is collected in six articles in the journal "Science", in addition to in a dozen complementary writings in other scientific publications.
The genome is the complete set of instructions of an organism, a book that is written with combinations of only four chemical units designated by the letters A, T, C and G (adenine, thymine, cytosine, and guanine) - these are called nucleotide bases.
For humans, this instruction manual contains about 3,000 million base pairs (or letters).
Scientists decode first complete sequence human genome of chromosomes
They are found in the twenty-three pairs of chromosomes inside the nucleus of all cells. Sequencing means determining its exact order in a DNA segment.
Two decades have passed since the first draft of the human genome made, separately, by Celera Genomics and the Human Genome Project.
That 8% had not been sequenced in large part because it is made up of very repetitive DNA regions that are difficult to align with the rest and with each other.
Current technology, capable of reading hundreds of thousands of letters at a time from the genome, has made it possible to do so.
Importance of scientists decode first complete sequence human genome
Genes of medical importance
The version without "gaps" of the new reference genome - called T2T-CHM13 - is composed of 3,055 million nucleotide base pairs and 19,969 protein-producing coding genes, the fundamental pillars of all the components of the organism. They perform most of the work in cells and are necessary for the structure, function and regulation of tissues and organs.
Of the protein-coding genes, the consortium found about 2,000 new ones. Most of them deactivated, although about a hundred can remain active, that is, producing proteins.
In addition, more than two million hitherto unknown genetic variants were discovered in those dark regions, 622 of which occur in genes of medical importance.
The researchers generated the entire genome sequence using a special cell line. It has two identical copies of each chromosome, unlike most human cells that carry two slightly different copies.
Among other things, the new DNA sequences added reveal never-before-seen details around the centromeres. They are sections in the middle of the chromosomes that play a fundamental role in their structure and in the correct segregation of them during cell division.
It has long been known that centromeres are poorly regulated in all types of diseases. Now "for the first time we can study 'base by base' the sequences that define these structures and begin to understand how they work," says Karen Miga.
The researchers also observed these new DNA sequences around telomeres - structures that, like caps, protect the integrity of chromosomes.
"The parts of the genome that we had not been able to study for more than 20 years are important for understanding the functioning of the genome, genetic diseases and human diversity and evolution," says Miga.
"In the future, when a person's genome is sequenced, we will be able to identify all the variants of their DNA and use that information to better guide their medical care," says Phillippy in a note from the NHGRI: "Now that we can see everything clearly, we are one step closer to understanding what it all means."
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