July 4, 2003 Mutations in a recently discovered gene can cause Parkinson's disease in patients with no family history of the disorder, according to a report in the June 30 on-line edition of the Annals of Neurology, the scientific journal of the American Neurological Association.
A research team led by scientists from the National Institute on Aging (NIA) in Bethesda, Maryland, discovered the mutations--in a gene called DJ-1--in a patient who had been diagnosed with the disease at the early age of 24 years.
"Showing that a mutation in DJ-1 can cause disease in the absence of a family history is an important point," said author Andrew Singleton, Ph.D., of the Molecular Genetics Section of the Laboratory of Neurogenetics at the NIA, who led the study.
"A concept that many scientists as well as lay-people forget is that just because there's no family history doesn't mean the disease isn't genetic," added Singleton.
In most patients, Parkinson's disease strikes in middle age or later, without a family history of the disorder. For this reason, Parkinson's has generally not been viewed as a genetic disorder.
However, recent discoveries of rare gene mutations that cause the disease in certain families--typically striking at younger ages--have focused attention on the genetic component of the disease, even among the majority with the "non-genetic" form of the disease.
"Non-genetic is probably the wrong term, because I think all Parkinson's disease possesses a genetic component. 'Typical Parkinson's disease' is a better term," said Singleton.
The gene DJ-1, located on chromosome 1, is among the most recent Parkinson's genes to be discovered. Mutations in this gene are at the root of Parkinson's disease that runs in two families in the Netherlands and Italy.
In the present study, Singleton led a multinational team from NIA and the National Institute of Neurological Disorders and Stroke, also in Bethesda, as well as researchers in Toronto, Canada; Caracas, Venezuela; Rotterdam, the Netherlands; and Rome, Italy.
The team hunted for variations in the DJ-I gene in 107 patients with Parkinson's, 69 of whom had no family history of the disease. In one of these cases of typical Parkinson's, the researchers discovered two separate mutations in the DJ-1 gene.
Although scientists still don't know what the protein product of the DJ-1 gene does in the body, much less how the mutations could lead to Parkinson's disease, they can use these discoveries as a starting place. While investigating the DJ-1 protein, researchers can determine which other proteins they associate and interact with, and also how the mutations affect these interactions. This detective work might lead, in turn, to the final common pathway that causes the death of brain cells in all forms of the disease.
In typical Parkinson's, a genetic variation or mutation might be insufficient to cause the disease by itself, but could increase the risk or affect the symptoms and progression of the disease. Combinations of several genes and environmental factors are likely required to cause most cases of Parkinson's.
The Annals of Neurology, the preeminent neurological journal worldwide, is published by the American Neurological Association, the world's oldest and most prestigious neurological association. The 1,400 members of the ANA--selected from among the most respected academic neurologists and neuroscientists in North America and other countries--are devoted to furthering the understanding and treatment of nervous system disorders. For more information, visit http://www.aneuroa.org.
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