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Largest-ever African genome study may give disease insights

4 November 2019
Appeared in BioNews 1022

New genetic variants found in an African population provide insights into human health, according to a large genome study.

Approximately a quarter of genetic variants found in the study of Ugandan populations have not been previously reported. The research demonstrated greater genetic diversity than previous genome studies predominately involving European populations, and offers disease insights and the potential to generate new therapies. 

'Africa is central to our understanding of human origins, genetic diversity and disease susceptibility,' said lead investigator, Professor Pontiano Kaleebu, director of the MRC/Uganda Virus Research Institute and the London School of Hygiene and Tropical Medicine Uganda Research Unit. 'There is a clear scientific and public health need to develop large-scale projects that examine disease susceptibility across diverse populations across the continent. That work should be integrated with initiatives to improve research capacity in Africa.'

The study conducted in southwest Uganda included genome-wide data from 6400 participants and whole-genome sequencing from nearly 2000 participants. The blood samples from these individuals were analysed to generate genotypes and test for markers such as glucose and cholesterol. Measurements such as height, weight and blood pressure were gathered from participants. The researchers also incorporated data on 14,000 people from different parts of Africa.

Researchers found ten new genetic variants in the study, of which nine are found only in Africans. They identified a particular genetic association known to cause alpha thalassemia, associated with levels of glycated haemoglobin. This genetic variant, found in 22 percent of African individuals, offers protection against malaria although it is associated with disease. Furthermore, the study authors said that measuring the levels of glycated haemoglobin, which is used as a diagnostic tool to identify diabetes, must be carefully used in the African population because of the risk of misdiagnosis. 

'Until we understand the differences between genetics in Western populations and other regions of the world, we are blindly applying drugs, treatments and diagnostic insights from European populations onto African people,' study joint-first author Dr Deepti Gurdasani, at Queen Mary University of London, told The Telegraph.

'Because of genetic diversity within the continent, we may gain insights into [diseases and treatment options] from studying tens of thousands of Africans that we would not find even when studying hundreds of thousands of Europeans,' she said.

'European ancestry populations make up 16 percent of the global population, but approximately 80 percent of participants in genetic studies,' Dr Alicia Martin at the Broad Institute in Cambridge, Massachusetts, who was not involved in the study, told New Scientist. 'This means populations of all other ancestry groups are vastly underrepresented.'

The study was published in the journal Cell.

SOURCES & REFERENCES
Genetic studies have missed important gene variants in African people
New Scientist |  31 October 2019
Largest ever genome study of Africans could lead to new disease treatments
London School of Hygiene and Tropical Medicine |  31 October 2019
Largest ever study of African genome will help fight racial bias in medical data, say experts
The Telegraph |  31 October 2019
Uganda Genome Resource Enables Insights into Population History and Genomic Discovery in Africa
Cell |  31 October 2019
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