Parkinson’s disease gene identified with help of Saskatchewan Mennonite families

"This discovery paves the way for further research to determine the nature of brain abnormalities which this gene defect produces," says Dr. Ali Rajput, a world expert in Parkinson's disease who has been studying the disease for 45 years and working with the main family in the study since 1983.

"It also promises to help us find ways to detect Parkinson's disease early, and to develop drugs which will one day halt the progression of the disease."

The abnormal gene is a mutated version of a gene called DNAJC13, identified by UBC medical genetics professor Matthew Farrer, who led the study.

Thirteen of 57 members of one extended Saskatchewan family in the study had been previously diagnosed with Parkinson's disease. Three other single cases from Saskatchewan and one family from British Columbia were also found to have the same mutation. All were of Mennonite background, a Christian group who share Dutch-German-Russian ancestry.

The findings were presented last week to the more than 5,000 delegates at the 16th International Congress of Parkinson's Disease and Movement Disorders in Dublin, Ireland.

Rajput and his son, fellow neurologist and researcher Alex Rajput, are long-time collaborators of Farrer. The research drew on the Rajputs' work over the past four decades. The research team also includes scientists from McGill University, the Mayo Clinic in Florida, and St. Olav's Hospital in Norway.

A key contribution is the Rajputs' collection of more than 500 brains and nearly 2,200 blood samples from Parkinson's patients. Farrer explains that confirmation of the gene's linkage with Parkinson's disease required DNA samples from thousands of patients with the disease and healthy individuals. He adds that the contributions of the Saskatchewan Mennonite family, who have asked to remain anonymous, were critical.

"A breakthrough like this would not be possible without their involvement and support. They gave up considerable time, contributed clinical information, donated blood samples, participated in PET imaging studies and -- on more than one occasion following the death of a family member -- donated brain samples," says Farrer, who holds the Canada Excellence Research Chair in Neurogenetics and Translational Neuroscience.

"The whole-hearted and unselfish commitment of this family is remarkable," Rajput says. "They went out of their way in every conceivable manner to help solve this mystery. We, on behalf of all the Parkinson's disease patients in this province, Canada, and around the world, are grateful to them for making this discovery possible."

In a Parkinson's patient, cells in an area of the brain called the substantia nigra (black substance) die and there are abnormal, round clumps of protein known as Lewy bodies inside the brain cells. Examination of the brains from the Mennonite family revealed the same Lewy body Parkinson's disease as seen in other patients.

Parkinson's disease is a progressive condition that causes symptoms such as tremors, slowness of movement, stiffness, and mental impairment. In most cases, symptoms appear after age 40. It is estimated that about one million people in North America and more than four million people worldwide are affected by the disease.