The Entire Human Genome Has Finally Been Sequenced after 20 Years

by Alisha Upadhyay

The Entire Human Genome Has Finally Been Sequenced after 20 Years

June 3, 2021

How does the science of Genetics help us? Why is Gene Sequencing so important?

"Having been part of the original Human Genome Project in 2001, and especially focused on the difficult regions, it's really satisfying for me to see this done even though it took 20 years."

- Researcher Evan Eichler, a genome scientist from the University of Washington in Seattle

Researchers have now sequenced the entire human genome, filling in the gaps in the historic first draft of the Human Genome Project (HGP). This is a turning point in science that would change the study of genomes forever. But the human genome sequence was not 100 per cent complete when it was first drafted and updated. However, the Telomere-to-Telomere (T2T) Consortium claims to have addressed the remaining 8% of the human genome that had been missing. 

What is the Human Genome?

A Human Genome is the entirety of the genes that make up an organism. Genes, on the other hand, are long strands of DNA. The human Genome is written in DNA, and though your specific genome is unique to you, 99.9% of it is shared by everyone. These strands are composed of adenine, thymine, guanine, and cytosine. It is your Genome that has the code which instructs your cells how they should behave. Cells corporate with each other to form tissues which in turn make organs and eventually form an entire organism. So the peculiar way you look and your structure is mainly due to your Genome.


What is Genome Sequencing, and how is it done?

If the term Genome sequencing gives you deja vu, it might be because it first made the news in 2003. Scientists took around two decades to sequence the human genome and still call it the first draft. However, it took the effort of hundreds of scientists and $3 Billion to get to that point. 

It makes one wonder, what is the point? The point is to know the billions of ways your adenine, thymine, guanine, and cytosine can be sequenced. It’s done by breaking your DNA into parts, then isolating it and sequencing these strands individually. The most common method is to use enzymes to make thousands of copies of these tiny strands and make them readable. This then helps in determining how your and my genomes are different. However, there still were gaps in this process. 

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The scientists investigated two sequencing technologies developed by Pacific Biosciences and Oxford Nanopore to fill in the gaps. They were significantly less precise at first than the method used to construct the genome sequence, but years of refinement enhanced their performance. They both have strengths that balance out one another’s flaws; thus the scientists could produce a fully complete human genome for the first time by combining both methods and adding around 130 million DNA bases to the HGP’s sequence. This project is still to be peer-reviewed which will test its practicality  

Human Genome sequencing can be a game-changer as it takes us further in solving some genetic diseases like ALS, Alzheimer’s, and Diabetes or even something as small as how we react to particular medications.  


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