Researchers at Mayo Clinic in Jacksonville, Fla. and the National Taiwan University Hospital in Taipei, Taiwan have discovered what to date appears to be the most common genetic risk factor for Parkinson?’s disease worldwide.
They believe the majority of people carrying this genetic mutation descend from a common ancestor about 4800 years ago. Their study was published Jan._9 in the online edition of Parkinsonism and Related Disorders.
Researchers found that ethnic Chinese individuals carrying a mutation they identified in the LRRK2 gene are over two times more likely to develop the disease than non-carriers. Given the population of China and the number of ethnic Chinese worldwide, this mutation may predispose more people to developing Parkinson’s disease than any other genetic factor. However, researchers say not everyone with the mutation develops the disease, and in those that do, other genetic and environmental factors are probably in play.
Mayo Clinic neuroscientist Matthew Farrer, Ph.D., lead author on the study, says this discovery is a small part of the ongoing genetic revolution in medicine. “Seemingly sporadic Parkinson’s disease may be a familial disorder, and we’re finding that the genetic risk factors for Parkinson’s disease are population specific,” he says.
In 2004 Mayo Clinic researchers were part of a team that discovered the LRRK2 gene and its role in Parkinson’s disease. This group and others went on to find a number of mutations in LRRK2, a gene that codes for a poorly understood protein, leucine-rich repeat kinase 2. One of the mutations, G2019S, has been shown to cause Parkinson’s disease in people with and without a family history of the disease. G2019S is an especially common cause of Parkinson’s disease in Berber Arabs and Ashkenazi Jews.
However, in contrast to the G2019S mutation, which is considered a disease causing mutation because it is rarely found in healthy, elderly people without Parkinson’s disease, the newly researched G2385R mutation, the subject of this study, does not always lead to disease. It is found in approximately 4 percent of the ethnic Chinese population without Parkinson’s disease, which is why researchers consider it a risk factor rather than a causal mutation.