Nigerian researchers, others uncover genetic variant that increases risk of Parkinson’s Disease in Africans

The Global Parkinson’s Genetics Programme (GP2) has announced the discovery of a genetic variant that increases the risk of Parkinson’s Disease (PD) in people of African and African admixed populations.

GP2 researchers identified the variant on the GBA1 gene as part of efforts to galvanise international and collaborative research into the genetics of Parkinson’s Disease and revolutionise treatment for the African and African admixed populations.

The GP2 researchers include the Nigeria Parkinson Disease Research (NPDR) network, the International Parkinson’s Disease Genomics Consortium (IPDGC)-Africa, University College London, the National Institutes of Health (NIH) in the United States, and 23andMe.

GP2 is a resource programme of the Aligning Science Across Parkinson’s (ASAP) initiative that is funded by the Sergey Brin Family Foundation and implemented by The Michael J. Fox Foundation for Parkinson’s Research (MJFF).

What is Parkinson’s disease?

Parkinson’s disease is a progressive neurological disorder that primarily affects movement control. It develops when there is a gradual loss of a specific type of brain cells known as dopaminergic neurons in a region of the brain called the substantia nigra.

These neurons produce dopamine, a neurotransmitter crucial in transmitting signals that regulate movement and coordination.

The loss of dopamine-producing neurons leads to a disruption in the brain’s ability to transmit messages related to movement and coordination effectively.

Symptoms include tremors, painful muscle contractions, difficulty speaking, and difficulty with walking. The disease gets worse over time, and there is no cure, but therapies and medicines can reduce symptoms.

The study

In a statement disseminated on its official website, the National Institutes of Health noted that, although further investigation is necessary to comprehend the role of environmental and other factors in these populations, the scientists uncovered that individuals carrying a single copy of the gene face about a 1.5 times greater likelihood of developing Parkinson’s disease compared to those without any copies. Meanwhile, those carrying two copies are approximately 3.5 times more susceptible.

The director, NIH Intramural Center for Alzheimer’s Related Dementias (CARD), Andrew Singleton, said to effectively treat Parkinson’s and truly any disease, there is a need to study diverse populations to fully understand what the drivers and risk factors are for these disorders.

Mr Singleton said 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.

Over the past few decades, researchers have found several genetic risk factors for Parkinson’s disease. Rare inherited cases of the disease have been linked to about 20 genes harbouring pathogenic variants – formerly known as disease-causing mutations — while more than 100 regions of the human genome are associated with more common, sporadic forms of the disease.

However, most of these findings are based on studies of people of European descent, and very few have been conducted on people of African descent.

Samples

For this project, the researchers conducted a Genome-Wide Association Study (GWAS) involving 1,488 people who had Parkinson’s disease and 196,430 people who did not.

The researchers collected DNA samples and analysed genetic data from individuals primarily from Nigeria and four sites across the United States. These data were combined with de-identified genetic and phenotypic data from 195,587 people of African American or Afro-Caribbean descent who consented to participate in 23andMe research.

A preliminary data analysis showed a significant association between Parkinson’s disease risk and the newly identified variant of the GBA1 gene. A review of previous studies also showed that this new variant rarely appears in people of European and Asian descent, suggesting it is almost exclusively linked to African ancestry.

A staff scientist at NIH CARD, Sara Bandrés-Ciga said, “We were completely surprised. The goal of the initial analysis was to help train GP2 researchers in Nigeria and other parts of the world on how to analyse GWAS data.”

Ms Bandrés-Ciga said the GBA1 variant had a significant association, while others did not suggest that it is strongly tied to Parkinson’s disease in this population.

Nigerian researchers

The NPDR network and UNILAG team are led by a Professor of Neurology in the Department of Medicine, Faculty of Clinical Sciences, College of Medicine, UNILAG, Njideka Okubadejo, who acknowledges the crucial role that the supportive research environment at the university and the commitment of the national and international partners played in the success of the team.

Ms Okubadejo said the GBA1 result is a step toward that future, where the research field is prioritising, learning from, and treating all people with Parkinson’s disease.

Other members of the UNILAG team collaborating with GP2 include: Associate Professor and Site Lead Investigator, Faculty of Clinical Sciences (FCS) Oluwadamilola ‘Lara’ Ojo, Osigwe Agabi (FCS), Francis Ojini (FCS), Ismail Ishola (Faculty of Basic Medical Sciences (FBMS), Francisca Nwaokorie (Associate Professor, FBMS), Roosevelt Anyanwu (Central Research Laboratory CMUL), and Arinola Sanyaolu (FBMS).

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The UNILAG Vice-Chancellor, Folasade Ogunsola, congratulated the team on the GP2 project for their impact on the latest discovery.

Ms Ogunsola, a Professor of Medical Microbiology, said the team’s input and impact on the GP2 further accentuates the university’s fast migration into a future-ready institution with imprints in various fields, including science.