A group of researchers from around the world published the first complete genome in a preprint article, which has not yet been peer reviewed. The consortium, Telomere-to-Telomere (T2T), is an open, community-based effort to complete the missing regions of the human genome.
Multiple announcements have been made in the past about the human genome being completely sequenced, but up until now, about 8% of the genome remained uncompleted. The new research serves as the first time that all 3.055 billion base pairs or letters of the human DNA code has been sequenced and corrects multiple errors in the previous sequences of the genome.
"This 8% of the genome has not been overlooked due to its lack of importance, but rather due to technological limitations. High accuracy long-read sequencing has finally removed this technological barrier, enabling comprehensive studies of genomic variation across the entire human genome," wrote the researchers in the paper.
The previously unsequenced 8% of the genome is part of the heterochromatic section, which contains highly repetitive sequences. While scientists initially thought that these regions did not contain any important genetic information, it is now known that abnormalities in these regions can have far reaching effects.
The scientists used two new DNA sequencing technologies that allowed them to fill in the gaps that earlier technologies were unable to fill, according to The Atlantic. Previous sequences of the genome were done using a method which cut DNA into small pieces. This method couldn't accurately sequence the more repetitive sections of the genome.
The new technologies used by the scientists allowed for longer DNA fragments to be produced and accurately sequenced, making it possible to sequence and study repetitive sections of DNA.
There is still work to be done in order to more fully understand the human genome, as only X chromosomes from a European sample have been studied. Y chromosomes and samples from other regions will also need to be studied. The scientists involved in the study believe that the technologies they used will make it possible to fully study Y chromosomes and other samples as well, and efforts are already underway to do so.