The entire human genome was mapped about 20 years ago. A team has achieved a gapless genome sequence, accounting for 8% of genetic information not previously known. The data that is missing may provide insight into the evolutionary journey of humans and our susceptibility to diseases. In 2003 a large group of scientists at the Human Genome Projec t unveiled the fruits of their labor: a nearly complete rendering of our genetic code. It was known that they hadn't gotten everything. They focused on reconstructing the parts of the genome that are less tightly packed because of limitations at the time. This still meant that the majority of the genome was mapped, but it also meant that the DNA in our Heterochromatin regions would not be known for a long time. The dark matter of our genetic structure is Heterochromatin. It's chunks of genetic material are densely packed and filled with repeated sequences of DNA, making it harder to translate and reconstruct into something readable. Thanks to advances in genetics and a few lucky breaks, scientists have been able to decipher the gaps. The Telomere to Telomere (T2T) consortium committed to fully mapping the genome after that. One of the breaks involved finding a cell line from those with a rare condition that left their cells with two identical copies of their father's genome, as opposed to both parents like usual. Even with machines now able to sequence DNA faster than ever before, the effort still required manual translation for the most complex bits. The team of scientists published their research on the first chromosomes by 2020. They were confident enough to release a preprint of their work by May 2021. Their full peer-reviewed work has finally been revealed in a new paper. Evan Eichler is a researcher at the University of Washington School of Medicine and co-chair of the T2T consortium. What we learn from this could very well change our current thinking about the variations inherent in our genes and how they have affected our evolutionary journey.
We now know that the repeated bits of DNA found in our Heterochromatin are important. In humans and other mammals, this DNA is thought to help structure the genome as a whole, which includes silencing other genes that could be harmful. Our centromeres contain structures that help ensure that chromosomes end up where they belong when cells divide.
We are getting complete information for the equivalent of one entire chromosomes, according to Eichler.
By having a full reference map, the authors say, we can better find and track variations in our genes that could tell us something about our genetics.
Hundreds of genes and parts of genes that are important to human health are now accessible for the first time thanks to the complete human genome.
The mapping efforts aren't done yet. The next step is to sequence the genome of the chromosomes that are mixed with both parents. They would like to sequence people's genes from across the world in order to better understand our genetics.
We will start with dozens and then hundreds and eventually have thousands, so that we can better represent the diversity of human genomes.
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