(ORDO NEWS) — The human genome was first sequenced in 2003. Since then, technological improvements have made changes, adjustments and additions, making the human genome the most studied vertebrate genome.
However, some gaps remain – including human chromosomes. We are pretty good at them, but there are still some gaps in the sequences. Now, geneticists have closed some of these gaps, giving us the first complete, missing, end-to-end sequence of the human X chromosome.
The achievement was accomplished thanks to a new technique called nanopore sequencing, which provides ultra-long reading of DNA strands, providing a more complete and consistent assembly.
This contradicts previous sequencing methods in which only short sections could be read at a time. Previously, geneticists had to put together these sections, like puzzles.
“We found that some of these regions, where there were gaps in the reference sequence, are actually among the richest for variations in human populations, so we missed a lot of information that may be important for understanding human biology,” said biologist Karen Miga from the University of California at Santa Cruz.
This is where nanopore sequencing begins. It consists of protein nanopores – nanoscale holes – installed in an electrically resistant membrane. Current is applied to the membrane, which passes it through the nanopores. When genetic material is fed into nanopores, a change in current can be translated into a genetic sequence.
Moreover, this technology reduces the dependence on the polymerase chain reaction, which enhances DNA by creating millions of copies.
It was this technique that Miga and her team used to study DNA obtained from a rare type of benign tumor of the uterus, an algal mole, along with other sequencing technologies to ensure that the final result was as complete as possible.
“Our results show that it is now possible to complete the entire human genome,” the researchers wrote in their article, “and the data presented here will allow efforts to build the remaining human chromosomes.”
The data obtained by the team is fully available on GitHub , an article was published in the journal Nature.
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