The first genome-wide association study on Parkinson’s disease in African populations has revealed a genetic variant that increases the risk of developing the disease.
Published in The Lancet Neurology, the study found a new genetic risk factor in GBA1 in people of African ancestry, which has not been seen studies on European populations. The authors say it could be a significant factor underlying Parkinson's disease in African populations. The variant (Rs3115534-G) was found to be present in 39% of the cases assessed.
Geneticist Ellen Sidransky at the National Human Genome Research Institute (NHGRI) was the recipient of one of this year’s US$3-million Breakthrough prizes — the most lucrative awards in science - for her discovery of GBA1.
Although Parkinson’s disease has been extensively investigated with respect to its environmental and genetic etiology in various populations, studies on people of African ancestry are rare.
The study showed that people of African ancestry who carry one copy of the Rs3115534-G variant, located on human chromosome 1, are about 1.5 times more likely to develop Parkinson’s disease compared to those without it. Those who are carriers of two copies of the gene have a 3.5-fold risk.
“These results support the idea that the genetic basis for a common disease can differ by ancestry, and understanding these differences may provide new insights into the biology of Parkinson’s disease,” says Andrew Singleton, director of NIH Intramural Center for Alzheimer’s Related Dementias (CARD), who co-led the study.
Researchers have found several genetic risk factors for Parkinson’s disease in other populations. However, previously identified variants appear in the part of genetic code that guides how the body manufactures glucocerebrosidase, an enzyme encoded by GBA1.
However, the newly discovered variant appears just outside the coding region, exerting its effect via modification of gene expression. “How and why it does that is still not clear,” says Mie Rizig, the study co-lead and clinical senior research fellow at UCL Queen Square Institute of Neurology, UK.