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Analysis of the genomes of hundreds of people from all over Africa has shed light on ancient migrations and modern disease susceptibility and resistance, revealing unexpected genetic diversity.
The genome is often described as the body’s instruction manual, and whole genome sequencing involves effectively reading the billions of bases of DNA in an individual.
New research on sequences of more than 400 people from the African continent is part of an attempt to address an imbalance in the genetic data available around the world, most of which come from people of European descent.
The work, published Wednesday in the journal Nature, reveals that Zambia may have been a key stopping point in the expansion of Bantu-speaking groups.
And it finds that populations living in an area may have significantly different genetic vulnerabilities to diseases.
“These are population groups that for the most part have not had their genomes sequenced before,” said Zane Lombard, associate professor of human genetics at the University of Johannesburg’s Witwatersrand, who helped lead the study.
“So the addition to our knowledge base is unique, significant and more than would be expected from a similar sample in other populations,” he told AFP.
In many ways, we live in the era of the gene, with a better understanding of the basic building blocks of our body that helps advance medical research and treatment and better explains how humans evolved and migrated around the world. .
But the picture of human genetic variation remains frustratingly incomplete, with the diversity of the world far from being represented.
Just 22% of genomic research participants come from a non-European heritage, with most of the genetic data available coming from just three countries: Great Britain, the United States and Iceland.
Efforts to correct have been underway for years in Africa, and Lombard’s team has been working with a consortium set up to improve genetic research on the continent to access whole genome sequences from 426 people enrolled in the ongoing studies.
The sample may seem relatively small, but it represents 50 ethnolinguistic groups from 13 countries, including some studied for the first time.
– ‘Scratch the surface’ –
Among the discoveries revealed by the sequencing was an unexpectedly large number of new so-called single nucleotide variants (SNVs), areas that differ from a reference genome and had not previously been identified in publicly available genome sequence data.
“This is significant because we are learning more about human genetic variation in general, discovering more differences that could be linked to diseases or traits in the future, and that can inform what we know about genetic diversity around the world,” Lombard said.
Uncovering variants is only a first step, but it will help identify which ones may be important to health outcomes and provide key data on the different vulnerabilities of populations.
“Africans are (often) assumed to have the same susceptibility or incidence to the disease, where this may not be a useful framework for specific groups,” Lombard said.
For example, the data showed that members of one group in Uganda had protective variants against severe malaria, while other groups living in the same country did not have the variant.
This could be the result, the study says, of the relatively recent migration of members of the unprotected group to parts of Uganda where malaria is endemic.
The sequence also offers insights into Bantu expansions – key migrations of Bantu-speaking people that have occurred several times over thousands of years.
Sequencing showed that Bantu groups in eastern and southern Africa had genetic similarities to Bantu speakers in Zambia.
So while recent work has theorized that at least one Bantu migration originated in Angola, genetic data suggests that Zambia may have been a key stopping point.
Despite all the revelations about the sequences, Lombard acknowledges that the work “is actually only scratching the surface of the more than 2,000 ethnolinguistic groups represented in Africa.”
Moving forward, the researchers hope to look at other types of variation in the sequences and add information from populations not studied.
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