The current human reference genome is deemed to be one of the most accurate versions, but some gaps in the DNA sequence have persisted even after more than twenty years of additions and improvements.
A team of scientists has reached a major milestone by determining the complete sequence of a human chromosome telomere to telomere (or from one end to another). The complicated task was made possible by the use of a bleeding-edge technology that facilitates extensive readings that can provide additional information.
Exploring the chain
Repetitive DNA sequences are encountered quite often within the genome and have possed major difficulties for sequencing as they lead to a large number of short reads, which seem to be identical. With the help of nanopore sequencing, researchers can now produce ultra-long reads which cover entire regions and feature unprecedented accuracy.
By filling the remaining gaps associated with the human genome, researchers can move to other areas of it where associations between sequence variants and diseases can be explored. It is also believed that new clues related to the evolution and enhancement of human biology may be found.
Some of the regions where gaps were present seem to contain an impressive amount of information related to variation in human populations, and more secrets may be discovered. Two of the researchers who contributed to the paper created a new consortium which aims to pursue a full genome assembly.
The new endeavor blends the use of nanopore sequencing with other sequencing technologies and advanced optical maps. The whole-genome assembly that has been obtained surpasses previous ones in quality, completeness, and accuracy by an impressive margin. There where some breaks that had to be addressed manually, including some in very difficult regions.
Further research will take place as the consortium aims to fully explore the remaining CHM 13 chromosomes.