Parkinson’s Disease Gene Variant Found in Some People of African Descent, Raises the Risk of Degenerative Brain Disorder

Every year, almost 90,000 people in the U.S. are diagnosed with Parkinson's disease, a brain disorder that causes slowness, balance and movement problems, and struggles in memory. In an effort to diversify genetic studies about Parkinson's disease, a global collaboration of researchers has led to the discovery of a gene variant unique to African ancestry.

(Photo: Pexels/ Kampus Production)

New Risk Factor of Parkinson's Disease

An international study has identified a genetic variant that increases the risk of Parkinson's disease in people of African ancestry and is not seen in those of European descent. Scientists led the research from the National Institutes of Health, the University College, London, and the University of Lagos, Nigeria.

Over the past decades, several genetic factors for Parkinson's disease have been identified by experts. Rare inherited cases of this condition have been linked to 20 genes that harbor pathogenic variants. At the same time, over 100 regions of the human genome are connected to the more common, sporadic forms of the disease. However, most of these investigations are based on studies of European populations, and very few have been carried out on people of African ancestry.

In this project, scientists performed a genome-wide association study (GWAS) on 1,488 people with Parkinson's disease and 196,430 who did not. They gathered DNA samples and analyzed genetic data from individuals from Nigeria and four other sites across the U.S.

A preliminary data assessment indicates a significant association between the risk of having Parkinson's disease and the newly identified variant of the GBA1 gene. Previous studies also revealed that this new variant is rarely observed among European and Asian populations, suggesting that it is almost exclusive to African descent.

Almost 3 in 10 people with Parkinson's disease assessed in the study show a mutation in the GBA1 gene. Further data analysis also reveals that the risk associated with the GBA1 variant is additive.

While more research is needed to understand better the role of environment and other factors in these populations, the experts discovered that those who carry one copy of the gene are nearly 1.5 times more likely to experience Parkinson's disease than those who do not have copies. Meanwhile, people taking two copies are about 3.5 times more likely to develop the brain disorder.

GBA1 Gene and Parkinson's Disease

GBA1 refers to the gene that provides instructions for making an enzyme called β-glucocerebrosidase, which is active in the lysosomes, the structures inside the cells that function as recycling centers. As a housekeeping enzyme, the β-glucocerebrosidase helps break down glucocerebroside into a sugar and a simpler fat molecule.

People carriers of GBA gene mutation have an increased risk of developing Parkinson's disease. It is still unclear how changes in GBA genes are related to this brain disorder, but studies suggest that gene mutation may play a crucial role in the faulty breakdown of toxic substances in neurons by disrupting the works of the lysosomes. Alternatively, the changes can also increase the formation of abnormal protein deposits. This results in the accumulation of protein deposits or toxic substances, which could kill the dopamine-producing neurons, causing abnormal movements and balance problems.