Researchers in Aotearoa and the Pacific have uncovered unusually high rates of a Parkinson's disease variant in Samoan and Tongan populations. The condition, known as PINK1 Parkinson's disease, is driven by a specific variant of the PINK1 gene (PINK1 L347P). Unlike most forms of Parkinson's disease, where the underlying cause remains unclear, scientists know exactly which molecular pathway is disrupted, creating new opportunities for targeted treatments.
Neurologist Dr Richard Roxburgh told RNZ's Our Changing World that a pattern emerged more than 15 years ago in Auckland neurology clinics, where doctors noticed an unusual number of young Pasifika patients with Parkinson's disease. "What was striking was that there were a number of people who are quite young and they were from Pacific families," he said.
Genetic testing provided the first clue when two unrelated patients — one Samoan and one Tongan — were found to carry two copies of the same rare PINK1 variant. A pilot study with eight Pasifika people with Parkinson's disease found that all five diagnosed before age 50 carried two copies of the variant, while none of the older participants did.
Research genetic counsellor Christina Buchanan said testing in Samoa was revealing. "In Samoa, we tested over 1200 people. One in 16 carried a single gene change in PINK1," she said. Because the condition is inherited in a recessive pattern, people typically need to inherit two copies, one from each parent, to develop the disease. "So 1 in 16 is a huge carrier number," Buchanan said. A recent international meta-analysis estimated that about one in 1300 people of West Polynesian ancestry are affected, a frequency higher than the threshold usually used to define a rare genetic disease.
The research also involved building awareness and breaking down stigma. Community advocate Aloese Lefono, working with Parkinson's New Zealand, established a dedicated Pacific Parkinson's Support Group in South Auckland after noticing few Pacific people were attending mainstream meetings. "Some of the Pacific Island people thought it was a curse," Lefono said. She added that Pasifika can be shy about sharing their illness, but the support group helps by providing a place where they feel comfortable: "They love coming together, speaking their own language, sharing their own experiences with the disease."
Researchers are now using donated skin samples from patients to create stem cells and laboratory-grown brain cells carrying the variant, allowing them to study the disease and test potential therapies. Dr Roxburgh said, "Because we know the cause, this opens the possibility of treatments." Buchanan believes a targeted treatment is not far away. "What everyone always quotes is five to 10 years. I truly believe that it is probably within the five years." Roxburgh added that if treatments are developed, they could also be applied to common Parkinson's disease: "If we can work out ways of treating this, it is possible that we'll be able to treat common Parkinson's disease using similar lines of treatment."