A $4.5 billion initiative to gather genomic data from African populations has been put forward to help fill the gaps in understanding the human genome.
Genome Wide Assay Studies (GWAS) have yielded a huge amount of insight into genetic associations with disease and roles in bodily function, transforming medicine. But the picture is still incomplete, and there are large gaps remaining.
While the genomes of Europeans and Americans has been well mapped, the genomes of Africans remain virtually a blank state despite having far more genetic diversity than any other region. Genome mapping has come a long way in the two decades since the first genome was sequenced, falling in cost from $3 billion to around $1000.
“Most genomic research on the African continent over the last two decades has largely been driven by agendas defined more by European and American investigators,” Ambroise Wonkam, a medical genetics professor and deputy dean of research at the University of Cape Town’s Faculty of Health Sciences, told AFP.
“The Three Million African Genomes (3MAG) project would require sequencing individuals carefully selected across Africa to cover ethnolinguistic, regional and other groups,” Prof Wonkam said. A similar study to map the genomes of 100 000 Asian people is underway.
The continent’s enormous genetic diversity no doubt holds a great number of surprises and important discoveries. Making his case in a comment in Nature, Prof Wonkam said that having access to such a diverse database would make it much easier to track down mutations.
“The aim is to capture the full scope of Africa’s genetic variation—for the benefit of all human populations and to ensure equitable access to genetic medicine.”
For example, a variant of the PCSK9 gene that is correlated with dyslipidaemia only came to light because it was 200 times more common in African Americans than Europeans.
Citing another example, Prof Wonkam said, “The inclusions of even a small number of black Americans in control cohorts probably would have prevented the misclassification of benign variants as causing cardiomyopathy.”
The relatively few GWAS of African populations that have been done also revealed a genetic susceptibility to type-2 diabetes that had previously gone unreported, and up to half of African populations have a gene variant associated with severe side effects to the HIV drug efavirenz.
When the genomes of 910 people of African descent were sequenced, it revealed large gaps in the ‘reference genome’ used by researchers around the world, Jesse Gillis, a researcher at the Stanley Institute for Cognitive Genomics in New York, noted in a study in BMC.
“Approximately 10 percent of DNA sequences—some 300 million base pairs—from these genomes were ‘missing’,” he stated.
Prof Wonkam has said that the study should mostly be funded by African governments, but international organisations should help foot the bill too.
Source: Medical Xpress
Journal information: Comment: Sequence three million genomes across Africa, Nature (2021). DOI: 10.1038/d41586-021-00313-7 , www.nature.com/articles/d41586-021-00313-7
