It’s been a minute since the first draft of the human genome was published back in 2001. As a joint effort by the Human Genome Project and the Celera Genomics, the first draft was released in 2001 and the final version in 2003 — 2 full years ahead of schedule. This accomplishment was a huge feat as it involved a massive collaboration between research groups in the US and around the world. The only thing is, the genome back then wasn’t really complete.
About 8% was missing…
That is not to say that the original effort was not an amazing achievement. We just have more powerful sequencing technologies now that can fill in the gaps!
Why Was the First Version of the Human Genome Incomplete?
Back in the 1990s, innovations in sequencing technology had given scientists the confidence to even attempt sequencing the entire human genome (roughly 3 billion base pairs). But despite the massive amount of DNA that was successfully sequenced and assembled, there were still pieces that remained a mystery.
This was because the sequencing technology at the time could only read bite-sized pieces of DNA. This is not a big deal for regions of the genome that are really distinct but is a challenge for repeated regions and genes that have duplicated themselves. Just think how hard it would be to piece together nearly identical sequences when given only short strings of nucleotides.
What Was Added to the New Version?
Since the first draft was published, small improvements to the human genome have been made over the past two decades. But in 2019, a company called Telomere-to-Telomere was founded by two biologists (Karen Miga and Adam Phillippy) with the intent to fill in the missing parts of the genome. Through their efforts, a group of 99 scientists cranked out data using current technology that can sequence much longer genetic fragments.
Here are some of their main contributions :
- Corrected mistakes made of previous versions of the genome.
- Uncovered ~8% of the genome that had previously not been sequenced. The genome is now 3.055 billion nucleotides long.
- Described over 2,000 new genes. Although most appear to be nonfunctional (inactivated by mutations), about 115 encode proteins.
- Identified new places in the genome that vary from one human to another.
Why Are Updates to the Genome Important?
The recent efforts in making the human genome more complete will push science forward, especially in the area of human medicine. For instance, of the new genes that have been described, it is plausible that at least some of them play a role in disease. Even the now-sequenced repeated regions likely hold biological importance. Once thought the be merely genome “junk,” these repetitive regions are now widely recognized to play important roles in the regulation of gene expression among other functions.
The newly updated genome will also improve the human reference genome — a representation of a “typical” human genome. This idealized genome, derived from the DNA of several individuals, aids in the assembly of other human sequencing efforts. It also provides a way for researchers and clinicians to identify mutations in patients that may contribute to their disease.
We Are Amid a Resolution Revolution in Biology
In a time of exciting scientific innovation, it is sometimes easy to forget how far we have come from just a few decades ago. The recent updates to the genome are often compared to making a blurry picture into a higher resolution one. This increased clarity allows scientists to scrutinize our genes with ever greater detail. This is just one more example of how the biological sciences are undergoing a “resolution revolution.”
Mission Bio has a similar goal in enabling scientists to see a richer picture of biology. With our Tapestri Platform, researchers can assess DNA and protein in individual cells, allowing them to dissect the complexity of cancer with exceptional detail. Tapestri can also characterize cells that have been genetically engineered, enabling advancements in disease modeling and cell and gene therapies.
The additions to the genome are certainly exciting and it is great to see how scientific capabilities have progressed over the years. We know more great things are to come and cannot wait to see what is around the corner.
Check out the recently published BioRxiv article detailing updates to the human genome.