DECODING THE GENETIC BASIS OF DIABETES IN AFRICANS

Priya Seetal

Seed funding from the South African Sugar Association (SASA) and other partners has led to a ground-breaking study which has its genesis in South Africa but has now spread to other African countries.


Late in 2009, SASA’s Nutrition Research Grants Panel approved a request from Dr Fraser Pirie at University of KwaZulu-Natal’s Nelson Mandela Medical School for seed funding for the first genome wide association study (GWAS) to identify specific genetic variants that contribute to diabetes risk in African subjects of Zulu descent.  


The panel saw it as an important study that would provide new information as prior to this, studies were confined to the European and Asian population, with limited studies done on the African population.  


The study has progressed to over 4000 African participants from South Africa, Nigeria, Ghana and Kenya.


The seed funding provided by SASA, Servier South Africa and The Victor Daitz Foundation led to collaboration with the world-class expertise of Oxford University’s Diabetes and Endocrinology unit, the Wellcome Centre for Human Genetics and the Sanger Institute based in Cambridge, UK. The study started with just over 1600 Zulu participants from Durban but due to significant interest from other research institutes, the study has progressed to over 4000 African participants from South Africa, Nigeria, Ghana and Kenya.  


The study has been published in highly respected medical journals such as Nature, Diabetelogia and Clinical Epidemiology with early results showing that there are differences between the European and African populations when it comes to the risk of developing diabetes.  Ultimately, this brings us closer to tailoring the prevention and treatment of diabetes in the populations of diverse African ancestries. SASA has been extremely privileged to have made a contribution to the study in a small but valuable way.   

The Human Genome

A genome is an organism’s complete set of DNA, including all of its genes.  Each genome contains all of the information needed to build and maintain that organism and pass life onto the next generation.  In humans, a copy of the entire genome – more than three billion DNA base pairs – is contained in all cells that have a nucleus.  


There is no one human being, with the exception of identical twins, that have the same genome and the differences between genomes are called variations. Your genome contains about 100 genome variations that occurred when you were conceived by your parents, which are unique to you. Other variations in your genome originated many generations ago and have been passed down from parent to child over the years, until they ended up in you. 


What is GWAS?

Genome-wide association studies or GWAS are a relatively new way for scientists to pinpoint genes across populations that may contribute to the risk of developing a certain disease. With the completion of the Human Genome Project in 2003 and the International HapMap Project in 2005, researchers now have a set of tools that make it possible to quickly and accurately find the genetic contributions to common diseases.  


The GWAS method searches the genome for small variations, called single nucleotide polymorphisms or SNPs (pronounced “snips”), that occur more frequently in people with a particular disease than in people without the disease.  Each study can look at hundreds or thousands of SNPs at the same time.


Because genome-wide association studies examine SNPs across the genome, they represent a promising way to study complex, common diseases in which many genetic variations contribute to a person’s risk of developing diseases. 


This approach has already identified SNPs related to several complex conditions including diabetes, heart abnormalities, Parkinson’s disease, and Crohn’s disease. Researchers hope that future genome-wide association studies will identify more SNPs associated with chronic diseases, as well as variations that affect a person’s response to certain drugs and influence interactions between a person’s genes and the environment.


GWAS and future medical care

The impact on medical care from genome-wide association studies has substantial potential.  Such research is laying the groundwork for the era of personalized medicine, in which the current one size-fits-all approach to medical care will give way to more customized strategies. The information will enable health professionals to tailor programs to prevent and treat diseases based on each person’s unique genetic makeup. 



Priya Seetal

Priya Seetal is Nutrition Manager at SASA


Sources
U.S Institute of Health and National Library of Medicine. 
Genome News Network (http://www.genomenewsnetwork.org/)



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