More than two decades after the design of the human genome was celebrated as a scientific milestone, scientists have finally got the job done. The first complete, gap-free human genome sequence has been published.
This more perfect sequence of the human genome is expected to pave the way for new insights into health, and what makes our species unique.
"The parts of the human genome that we haven't been able to study for more than 20 years are critical to our understanding of how the genome works, genetic disease, and human diversity and evolution," said Dr Karen Miga, a scientist at the University of California, Santa. Cruz is co-leading the international consortium behind the project.
To date, about 8% of the human genome is missing, including large highly repetitive sequences, sometimes described as "junk DNA". In reality, however, these repetitive sections were omitted due to technical difficulties in sequencing them, not due to lack of interest.
Quoted from The Guardian, Monday (4/4/2022) sequencing the genome, the picture is like slicing a book into pieces of text and then trying to reconstruct the book by putting it back together.
Loose text that contains a lot of common or repetitive words and phrases will be more difficult to put in the right place than more unique chunks of text.
Well, scientists were able to simplify this puzzle further by using an unusual type of cell that contains only DNA inherited from the father (most cells in the body contain two genomes - one from each parent). Together, these two advances allowed them to decode the more than 3 billion letters that make up the human genome.
"In the future, when a person's genome is sequenced, we will be able to identify all the variants in their DNA and use that information to better guide their health care," said Dr Adam Phillippy, from the National Human Genome Research Institute in Maryland, United States.
"Completing the sequencing of the human genome is really like putting on new glasses. Now that we can see everything clearly, we are one step closer to understanding what it all means."
One area of interest is that sections of the genome with many repeating stretches include those where most of human genetic variation is found.
The variability within this region may also provide important clues about how our human ancestors underwent rapid evolutionary changes that led to more complex cognition.
This work is also likely to lead to a better understanding of the mysterious components of the genome known as the centromere. They are dense bundles of DNA that hold chromosomes together and play a role in cell division, but until now were considered unmapped because they contained thousands of repeating sequences of DNA sequences.
The science behind the sequencing effort and some of the initial analyzes of new genomic regions is outlined in six papers published in the journal Science.
"Opening up this new part of the genome, we thought there would be genetic variation that contributes to many different traits and risk of disease. There are aspects like this, we don't know yet what we don't know yet," said Rajiv McCoy, of the University of Johns Hopkins.