More than 20 years after the first survey of our genome, a new updated variant is presented. Thanks to technological development, it has been possible to read parts that were previously hidden.
When a drawing of the human genome was first published in 2003, it was a huge step forward. By then, a large crowd of researchers had managed to find out the order of the base pairs that make up the human DNA strand. The gene map has been of great importance to researchers around the world.
The survey has enabled knowledge of, among other things, hereditary diseases and contributed to finding new treatments. At the same time, it has been clear that information has been lacking. But despite the fact that several updates have been made over the years, about 8 percent of our genome (genome) has more or less been shrouded in obscurity. Up until now.
– We have wondered what is hidden there in the dark and now it is as if we have turned on the light and can see what is there, we have got sharper glasses, says Mattias Jakobsson, professor of genetics at Uppsala University.
Fills important gaps
In total, six scientific studies with researchers from 30 different departments are published in the scientific journal Science. The work has generated an updated and more complete map of our 20,000 genes that go by the name T2T-CHM13.
– It will be an incredibly good tool for researchers and others who work with genetic material and fill important knowledge gaps. If it would only generate ten percent of everything that the first survey has led to, it would be fantastic, says Jakobsson.
He describes it as the ends and middle parts of the chromosomes that have now been mapped. The fact that the project has been able to be carried out is mainly due to the fact that the techniques for DNA sequencing, ie the method of determining the order of the building blocks, have advanced. This allows you to read longer pieces of DNA than before. It can be compared to a puzzle that has now been given larger pieces and then becomes easier to lay.
“Mysterious feeling”
There have been various theories about what was hidden in the 8 percent that were not previously mapped.
– Ten years ago, we were very excited about what would be in these regions, the feeling was that it could be genes that controlled crucial functions. It was almost a mysterious feeling about what could be hidden. But it was rather fewer genes that generally have a small impact on our characteristics and diseases, says Mattias Jakobsson.
Photo: Johan Hallnäs / TT
The new gene map will probably be used primarily in research. But there is also a direct benefit to some patients. At Karolinska University Hospital in Solna, Anna Lindstrand, chief physician and professor of clinical genetics, has already used the new reference clinically. She has been able to do this because the information was public on a website before it was published in Science.
– We have mapped a very rare chromosomal abnormality in a patient using T2T. This is one of the areas where the new reference can become clinically important, she says.
Because it requires extensive technology and data capacity to make a gene mapping in the way done by the researchers, nothing will be done as a routine in the first place. It will also take time before the old map is completely replaced with the new one.
Just a hereditary predisposition
In addition to closing knowledge gaps, the new gene map differs from the old one in another way. All people have double sets of their inherited traits, one from the mother and one from the father. But the genes that the researchers have now mapped come from an egg cell that has divided without being fertilized and therefore only has the mother’s genetic predisposition. This has made them easier to read.
– The usual reference genome is based on genetic information from about 60 people. This means that the new T2T does not in the same way reflect the variability that exists naturally among humans. It is more complete but not as complex as the previous one, says Lindstrand.
In the longer term, she is convinced that the clinical use will be extensive and be able to contribute to understanding more diseases and also be able to find treatments.
—It is a fantastic work that the researchers have done that will lead us to new discoveries and increased understanding of our genome. But we also know that we do not know everything yet, says Mattias Jakobsson.
Facts: T2T
In 2003, what was then stated to be the in principle final survey of the human genome was published. Pretty soon it became clear that there were parts that were missing.
Over the years, additional information has been added, but about 8 percent has been missing until now.
In 2018, the Telomere-to-Telomere Consortium (T2T Consortium) was founded by Karen Miga, of the University of California, and Adam Phillippy, of the National Human Genome Research Institute. There, experts in genetics collaborated to map the remaining 8 percent of the genome. The work is funded by the American National Human Genome Research Institute.
On 31 March 2020, a new reference map for the human genome will be published under the name T2T-CHM13 and will replace the previous GRCh38.
The researchers estimate that now only about 0.3 percent of the genome has not been mapped.
The fact that the mapping could be done is mainly due to the fact that the techniques available for DNA sequencing have become more powerful. With standard methods, 150-200 base pairs are read at a time. Now the researchers have used so-called long reading that can handle 100,000 base pairs per sequence.
[related_posts_by_tax taxonomies=”post_tag”]
The post Human genome mapped – for real appeared first on Gamingsym.