After 20 years, scientists reveal the most complete sequence of the human genome

There is still a need to put some final touches on the map of the reference genome, as the updated genetic map will undoubtedly help us understand the biology of the body

The Human Genome Project was one of the most important recent scientific achievements; Since its official launch in 1990, it aimed to monitor the complete human genome sequence, and then know the genetic bases that drive the cell to perform its functions or whose mutations sometimes cause the emergence of diseases.

Indeed, in 2003 he announced the first and largest of its kind to sequence the human genome. However, more than 15% of it was unknown at the time; At the time, genetic monitoring techniques were unable to identify large parts of the DNA.

Because these missing pieces of the genome contained frequently duplicated genetic sequences, some scientists dismissed them as nonfunctional or "junk DNA" genes. In addition, the previous reference map of the genome contained some errors. With the tremendous development in technology, scientists were able to reduce these unknown gaps to 8% in 2013.

Recently, 6 independent research studies - published in the journal " Science " on March 31, revealed a more complete map of the human genome, correcting a number of errors that were present in the previous reference map and completing the missing large genetic pieces .

An international consortium of nearly 100 scientists collaborated in this effort, led by Adam Felipe of the National Human Genome Research Institute, Karen Mega of the University of California, Santa Cruz, and Evan Eckler of the University of Washington.

Their work yielded a complete genetic map free of unknown gaps, except for the Y chromosome, which is responsible for producing males. This genetic map is the largest genetic sequence ever detected.

Repetitive and functional sequences

According to a press release published by the Howard Hughes Medical Institute, the human genome consists of more than 6 billion single letters spread over 23 pairs of chromosomes.

In order for scientists to know the complete genetic sequence of these letters, they must fragment the DNA into pieces hundreds to thousands of letters long. These individual letters in each segment are then read by genetic sequencing monitoring techniques, and then put together in the correct order to produce the complete genetic sequence.

Some regions of the genome, however, contain many repeats of the same letters, making them among the challenges to properly assembling the segments.

For example, the centromere - the special part of the chromosome that connects the two halves of the chromosome together - contains repeating sequences of these letters. The centromere plays a pivotal role in cell division.

Complete genetic sequencing

Hence, these repeated letters perform a vital function and cannot be classified within the non-functional gene sequences that the scientists omitted in the previous reference map because they contain repeating letters. In addition, new genes have been identified - containing repeating sequences of letters - that help species adapt.

Therefore, revealing all the missing pieces of DNA has become an urgent requirement for scientists in recent years. This goal is made possible today thanks to the tremendous development in genetic sequencing techniques.

Indeed, scientists have relied on new technologies that can read a million letters of DNA at a time with great accuracy. They established an international union, in order to monitor the letter sequences that make up each chromosome from its end - which is known as the telomere - to its opposite end, and then the union was called "telomere-to-telomere" or for short "T to T". (T2T).

In these studies, the researchers also used a distinct type of "cell line" that contains two identical copies of each chromosome, rather than the majority of human cells that carry two slightly different copies.

Promising addition

This international consortium was able to collect and sequence sequences of previously unknown parts of the human genome. Most of these characters are located in the telomere as well as in the centromere. This massive research effort has added nearly 200 million pairs of genetic letters to what we know today about the human genome.

According to the report , published by Science Alert, Felipe says, "Finishing the entire human genome sequence was like wearing new glasses. We can now see everything clearly."

"The parts that we didn't know for the past 20 years are important for understanding how the genome works, genetic disease, human diversity and evolution," says Mega, who also chairs the consortium of researchers.

This map of the reference genome still needs to be finalized; The Y chromosome still needs to be completed. However, the updated genetic map will undoubtedly help us understand the body's biology.