Human genome: they manage to decipher its “grey zone”

An international research consortium published the first complete sequence of the human genome that reveals new genes and will shed light on hereditary diseases and human evolution, scientific sources reported yesterday.

Until now, all genomic studies were based on and used as a reference the human genome sequence produced more than two decades ago and cataloged as GRCh38 of the Human Genome Project, which was a success at the time and revolutionized medicine, although due to the technological limitations 8% of the genome was left undisclosed.

“The genome sequence from 21 years ago got most of it right (92%), but it left out difficult regions that were highly repetitive,” explained Evan Eichler, a researcher in the Department of Genomic Sciences at the University of Washington, who participated in the study. the first draft.

Now the Telomere-to-Telomere (T2T) Consortium, of which Eichler is co-chairman and which has the participation of more than 100 researchers from dozens of international research centers, has achieved the most complete assembly to date for any mammal, they explained from the Information and Scientific News Service (SINC).

“This project was not possible until the sequencing technology for large DNA fragments did not reach a sufficient degree of quality,” said Alfonso Valencia, director of Life Sciences at the Barcelona National Supercomputing Center (BSC).

According to the researcher, in this study, funded by the National Human Genome Research Institute (NHGRI), 99% reliability is achieved by sequencing fragments that can be up to 200 MB of genetic information, equivalent to to a human chromosome from start to finish.

The research was compiled into six scientific studies published yesterday in the journal Science, in addition to other articles in other publications.

centrometers

Eichler said the sequence provides “the first complete view of all genes, adding some 120 new protein-coding genes that had not been previously characterized.”

But it also offers, for the first time, the complete vision of the centromeres -the parts of the genome important for segregation-, and “the short acrocentric arms of chromosomes 13, 14, 15 and 21, where the ribosomal DNA genes reside that are important for a cell’s protein production,” Eichler said.

Scientists now have a gapless sequence of the roughly 3 billion bases (or ‘letters’) in our DNA, critical information for understanding the full spectrum of human genomic variation, as well as genetic contributions to certain diseases.

The analysis of the latest version of the genome sequence will contribute significantly to the knowledge of chromosomes, including more precise maps of five chromosome arms, which will open new lines of research. This will help answer basic biology questions about how chromosomes properly segregate and divide.

“An incredible scientific achievement”

“Generating a truly complete human genome sequence represents an incredible scientific achievement, providing the first comprehensive view of our DNA footprint,” said Eric Green, director of NHGRI.

He added that “this critical information will bolster ongoing efforts to understand all the functional nuances of the human genome, which in turn will enhance genetic studies of human disease.”

A complete genome will also improve the location and discovery of genetic variables and, in doing so, “improve our ability to map complex diseases,” Eichler added.

The complete sequence of the human genome will be especially valuable for studies that aim to establish comprehensive views of human genomic variation, or how people’s DNA differs, vital insights for understanding genetic contributions to certain diseases and for using genome sequencing as a routine part of clinical care in the future, the researchers explained.

fundamental pieces

For José Manuel Bautista, Professor of Molecular Biology at the Complutense University of Madrid, this work -in which he does not participate- allows us to discover a part of the chromosomes that is important for their function; “It is as if we discovered after 20 years that the cars we see circulating have a clutch and that there are gear changes”.

“Knowing the pieces that make biological machinery work that has to do with the transmission of heredity allows us to understand elements of human biological history and discover some mechanisms that may have relevance in reproduction”, highlights the scientist.

This first complete sequence that covers each chromosome from end to end, without gaps and with unprecedented precision, is accessible to the entire scientific community.

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