Largest ever genome study of Africans could lead to new disease treatments

Map of Africa

Around a quarter of the genetic variation identified in the study, which is published in the Journal Cell, had not been discovered before. The study also found a higher level of genetic diversity in the Ugandan population than in similar studies of European populations.

Lead author Dr Deepti Gurdasani from Queen Mary’s William Harvey Research Institute said: “Most population genetics studies involve Western populations. We developed a rich, diverse resource using genome wide data from 6,400 Africans, including whole genome sequencing of nearly 2,000 people. Other researchers can use this data to improve the detection of genetic causes of disease – particularly those that disproportionately affect Africans and people with African ancestry.”

Study points to regular migrations dating back 4,500 years

She continued: “Modern Uganda appears to be a complex mosaic of many different communities that have migrated from surrounding regions – and from Europe and the Middle East. These migrations appear to have taken place regularly and date from just 300 years ago to around 2500 BC.”

The academic researchers collected and analysed genome-wide data from 6,400 people from a rural community in Uganda.

The team also incorporated data on 14,000 individuals from different parts of Africa. This allowed them to examine genetic determinants of traits within the population.

Dr Gurdasani said: “The combined study identified new genes associated with several diseases. These included ten new associations, of which nine are only found in Africans and would therefore not have been found in even the largest study involving Europeans.”

Important finding around diabetes

These discoveries included a genetic variant that causes thalassemia present in 22% of Africans that is associated with glycated haemoglobin, an indicator commonly used in the diagnosis of diabetes. This particular variant is thought to have become more frequent among African populations because it can prevent severe malaria.

As glycated haemoglobin levels are often used to diagnose diabetes, Dr Gurdasani says it is possible that diabetes may be misdiagnosed in some Africans if glycated haemoglobin is used as a diagnostic tool.

Before this project, which was largely funded by the United Kingdom’s Medical Research Council and Wellcome, only a few hundred whole genome sequences of African people had been completed. Researchers largely relied on genetic data from African-Americans which does not reflect the continent’s full diversity.

The research illustrates the need for globally diverse genetics research.

Another lead investigator, Professor Pontiano Kaleebu, who is the Director of the MRC/Uganda Virus Research Institute & London School of Hygiene & Tropical Medicine Uganda Research Unit, said: “Africa is central to our understanding of human origins, genetic diversity and disease susceptibility. There is a clear scientific and public health need to develop large-scale projects that examine disease susceptibility across diverse populations across the continent.”

More information:

• Uganda Genome Resource enables insights into population history and genomic discovery in Africa; D.Gurdasani et al; DOI: 10.1016/j.cell.2019.10.004
• You can find the article at https://www.cell.com/cell/fulltext/S0092-8674 (19)31120-1
• Study biomedical sciences or the medicine MBBS at Barts and The London School of Medicine and Dentistry, including on our Malta programme. We also offer an MSc in genomic medicine.