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The most comprehensive human genome sequencing to date has been completed

  Twenty years ago, scientists announced that they had read all the deoxyribonucleic acid (DNA) of a person. In fact, they missed a little. Now, thanks to improvements in DNA reading methods, scientists can finally read the entire human genome from beginning to end! According to reports, American scientists have sequenced 3.055 billion base pairs of the entire human genome. Compared with previous results, the new results have added 200 million base pairs and more than 2,000 genes.
  Humans have tens of thousands of genes, which are stored in DNA molecules. Genetic information exists in the form of 4 bases (C, G, T, and A). Two bases pair with each other to form base pairs.
  Scientists started the human genome sequencing project in 1990 and published the first draft of the human genome in 2001. But at that time, the gene components had to be read in small pieces, and then reassembled together, and it was impossible to put some highly repetitive fragments back in place. Subsequently, geneticists continued to improve, but the focus was still on improving the accuracy of existing sequences rather than adding new ones, and there were still about 8% sequence deletions or errors.
  The new version of the genome is drawn by the “telomere to telomere” (T2T) consortium. The alliance is led by Karen Mega of the University of California, Santa Cruz and Adam Philippi of the National Human Genome Institute.
  The researchers chose to read DNA from a cell line called CHM13. The cell line is derived from a vesicle-like fetus, a condition of pregnancy failure, which can be cultured in the laboratory. Philippi said: “CHM13 is unique in that it is not anyone’s genome.” Every piece of
  DNA in ordinary human cells has two copies, and there are often major differences, one from the mother and the other from the father, which makes Precise sequencing of DNA becomes more difficult, because it is very tricky to figure out what are the mistakes in the sequencing process and what are the real differences. Using CHM13 avoids this problem because the two copies are almost identical.
  To assemble the genome sequence, the research team used two technologies: one is a sequencing technology that can read very long (more than 1 million base pairs) fragments; the other is extremely accurate and can handle very small differences Fragmentation (such as multiple copies of the same gene) technology.
  In July 2020, the team announced the complete sex-determining human X chromosome. Now, they have released the complete human genome. The new version adds nearly 200 million base pairs and 2226 new genes over the previous version. It is the biggest improvement since the first release of the human reference genome.

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