In a collaborative effort, researchers in Germany and the USA sequenced the genomes of 32 people representing 25 population groups from East and South Asia, Africa, Europe and North America.
'For each human individual that participated in the study, we identified not one but two genomes – one for each set of chromosomes,' said Dr Jan Korbel, group leader at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, and a lead author on the study. He continued: 'Humans have two sets of chromosomes, which they receive from their parents. Previously we could not distinguish whether genetic variation came from one chromosome set or the other.'
Previously, differentiating between the genomes inherited from each of a person's parents required a comparison with their DNA, too. However, this work shows that it is now possible to map the entirety of a person's genetic makeup without needing to do this.
The use of long-read sequencing technologies provides a level of resolution not seen before; 68 percent of the genetic variations found by the researchers are not discoverable using previous technologies.
The long-read technology used in the study was particularly effective at resolving regions of highly repeated sequences and other long regions of variation known as structural variants. These can be harder to spot using shorter DNA reads than the types of mutations people are often more familiar with, such as single-letter changes in the DNA code.
The team explained, in the paper published in Science: 'the largest gains in sensitivity have been among structural variants – inversions, deletions, duplications, and insertions ≥50 [base pairs] in length.'
The findings of this study not only provide a greater understanding of the genetic variation among people, but bring us closer to more wide-spread use of personalised medicine. Being able to sequence an individual patient's genome with high fidelity means that tailored therapeutic programmes can be applied with greater confidence.
Co-first author Dr Bernardo Rodriguez-Martin of EMBL said: 'These genomes will enable a new wave of scientific discoveries about the biology of the human genome and the connection between genetic variation and disease'.