When Dr. Lara M. Lange and her team started gathering genetic data for their Parkinson's study, they noticed something troubling: nearly all previous research had come from people of European ancestry. Yet the genetic causes of Parkinson's disease work differently depending on a person's background.
"Before we can make genetically targeted therapies available worldwide, we need to understand which genetic causes play a role in different population groups," Dr. Lange said.
The study, published in The Lancet Neurology in 2026, analyzed genetic information from nearly 100,000 people across 11 world regions. What made this research stand out was its diversity — nearly a third of the participants came from Africa, Latin America, and Asia, regions largely missing from previous Parkinson's genetics research.
At the center of the investigation were two genes called GBA1 and LRRK2. Both contain instructions for enzymes that act like tiny garbage disposals inside nerve cells. When these genes have certain variants, the cleaning system breaks down, allowing harmful proteins to build up and potentially trigger Parkinson's. Both genes are already targets of experimental drugs designed to fix the problem.
The researchers discovered that while GBA1 and LRRK2 matter in every region they studied, the specific variants people carry differ dramatically depending on where their families come from. A variant common in West Africa might be rare in South Korea, and vice versa.
This matters because precision medicine — treatments tailored to a person's genetic makeup — only works if doctors know what to look for. If genetic tests are built only around European variants, patients from other backgrounds may never learn why they developed Parkinson's. They could also miss out on new therapies currently being tested almost exclusively in Europe and North America.
The work was part of the Global Parkinson's Genetics Program, an international collaboration that brings together research centers from around the world. Dr. Christine Klein, another member of the research team, said such a diverse study would have been impossible without this partnership.
"This study is an important first step toward truly global precision medicine for Parkinson's," Dr. Lange said. The hope is that future patients everywhere — not just in wealthy nations — will eventually benefit from treatments designed with their genetic backgrounds in mind.