The first human "pan-genome" was unveiled by scientists on Wednesday. It lists the most comprehensive range of genes in the human species to date, with the hope that it will help explain a range of diseases. It was featured in a series of scientific papers in the journal Nature by a group of scientists gathered in the Human Reference Pan-Genome (HPRC) consortium.

It compiles the genomes of 47 individuals of various origins, and is expected to gather the genomes of 350 individuals by mid-2024. Of these 47 people, who are anonymous, more than half come from Africa, a third from the Americas, Asia has six individuals and Europe has only one, an Ashkenazi Jew. Oceania is not represented. The announcement of this pan-genome was hailed as "ushering in a new era for genetic diagnosis" by geneticist David Adelson of the Australian University of Adelaide.

A first genome in 2003

A first human genome, which brings together all the genetic material specific to a man, was sequenced in 2003. It has served as a reference point for other human genomes published since. Above all, it has made it possible to identify genes responsible for specific diseases, to initiate research towards more personalized medicine and to shed light on the mechanism of human evolution.

But 70% of the sequences of this first genome came from a single individual (who had responded to a classified ad in a newspaper in the American city of Buffalo, in 1997) the rest from twenty other people. This has limited its use for populations of other ethnic origins.

Less than 1% difference

The genome is the genetic blueprint of any organism. It contains all the DNA elements incorporating the instructions to enable it to live and develop. The genome of two individuals is more than 99% identical, but the remaining differences may facilitate the onset of certain diseases in one individual rather than another.

The reference pan-genome could help shed light on these differences in genetic samples, said Benedict Paten, a researcher at the University of California and co-author of the study. "This will improve genetic testing and at the same time provide a better understanding of the contribution of all kinds of genetic variations on health and disease," he told a news conference.

Improving transplants

Another co-author of the study, Erich Jarvis, of the Rockefeller University in the United States, provided as an example the groups of genes, known as the major histocompatibility complex (MHC), that are involved in the functioning of the immune system. "Until now, it was impossible to study the diversity of CMMs," as it is so great between individuals, said the researcher. Progress in this area would have beneficial consequences for organ transplantation, in order to avoid rejection.

For David Adelson, the Australian geneticist, this first edition of the pan-genome has already increased the accuracy of detecting genetic changes by about 34%. The project "will benefit people of all backgrounds, unlike the current reference genome which does not reflect the diversity of humanity," he told AFP.

A real challenge

The pan-genome represents a "milestone in human genetics", but also a challenge, recalled two American experts quoted in Nature, Arya Massarat and Melissa Gymrek. Beyond the inclusion of footage from people belonging to underrepresented groups, the adoption of this new framework will require training for scientists.



In any case, "it will facilitate the discovery of genetic variants that influence physical and physiological traits and, hopefully, lead to health breakthroughs for many people," they said.

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