Scientists have finally completed the human genome project, more than two decades after the draught human genome was lauded as a scientific milestone. The first full, gap-free sequencing of the human genome has been released ahead of schedule, paving the door for fresh insights into human health and the characteristics that distinguish our species from others.
Scientists at the University of California-Santa Cruz and other institutions collaborated on the project, which was led by Dr Karen Miga. Dr Miga explained that the project’s findings are important for our understanding of how the genome works, genetic diseases, human diversity and evolution, and how humans have evolved over time.
Until recently, over 8% of the human genome remained undiscovered, including extensive lengths of highly repetitive sequences, which are commonly referred to as “junk DNA.” In actuality, however, these repeated passages were left out owing of technical challenges in arranging them, rather than a lack of interest on the part of the author.
Genomics is analogous to cutting apart books into little pieces of text and then stitching them back together again to attempt to recover the original book. The placement of longer stretches of text that include a large number of often used or repeated words and phrases would be more difficult than the placement of shorter, more distinctive bits of text. Fortunately, advances in “long-read” sequencing methods, which decode large portions of DNA at once – enough to catch multiple repetitions – have made it possible to overcome this obstacle.
Using a unique cell type that solely carries DNA inherited from the father (most cells in the body have two genomes – one from each parent), scientists were able to reduce the issue even more, leading to a breakthrough. The combination of these two breakthroughs enabled them to decode the more than 3 billion letters that make up the human genome.
According to Dr. Adam Phillippy of Maryland’s National Human Genome Research Institute, who is also co-chair of the consortium, “in the future, when someone has their genome sequenced, we will be able to identify all of the variants in their DNA and use that information to better guide their healthcare.” “Completing the human genome sequencing was like putting on a new pair of spectacles,” says the author. With everything now in full view, we are one step closer to comprehending what it all signifies,” says the author.
One point of interest is that the regions of the genome with a high number of repetitive stretches are also the regions where the majority of human genetic diversity may be discovered. These variations may also give important information as to how our human predecessors experienced fast evolutionary changes that resulted in the development of more sophisticated intellect.
The research is also expected to contribute to a better understanding of centromeres, which are mysterious components of the genome that have remained a mystery. They are thick bundles of DNA that keep chromosomes together and play a function in cell division, but they were previously thought to be unmappable because they include hundreds of sections of DNA sequences that repeat over and again. Now, researchers have discovered that they are mappable.
Six publications published in the journal Science describe the science underlying the genome-sequencing endeavour as well as some preliminary analysis of the newly discovered genomic regions.
Rajiv McCoy, a researcher at Johns Hopkins University and a member of the Telomere to Telomere (T2T) project, said that by opening up these new sections of the genome, “we believe there will be genetic diversity contributing to many different features and disease risk.” “There’s a part of this that’s like, ‘We don’t know what we don’t know yet,'” says the author.