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TUESDAY, July 1, 2003 (HealthDayNews) -- New research suggests a single defective gene caused a young woman to develop Parkinson's disease -- even though her family had no history of the illness.
The finding could help unravel some of the mystery surrounding the inheritability of the brain disease.
An estimated 1 million to 1.5 million Americans have Parkinson's, which causes tremors, difficulty walking and rigid muscles. In severe cases, patients can develop dementia and die, but medications have let many lead fairly normal lives.
The causes of Parkinson's aren't clear, although many experts think environmental contamination, especially from pesticides, may be at least partially responsible.
In a tiny number of cases, however, Parkinson's appears to be inherited. Researchers have found that the illness runs in two Dutch and Italian families. A mutated gene appears to cause the disease to appear in some members of the families, especially the young.
Inherited Parkinson's disease "is considered a scientific curiosity as it is thought to be rare," explains Dr. Paul Tuite, an assistant professor of neurology at the University of Minnesota.
To better understand the mutated gene, an international team of researchers decided to investigate whether the gene could cause the disease in other families, including those that had not encountered the illness. The researchers looked for mutations in the gene, known as DJ-1, in 107 Parkinson's patients who had developed the illness before the age of 50. Only 38 had a family history of the disease.
The researchers -- from Canada, Italy, the Netherlands and the United States -- report their findings in a study that will appear in an upcoming issue of the journal Annals of Neurology. The journal published the study online June 29.
The researchers found a mutated gene in a single 29-year-old patient, a Hispanic woman, who developed the disease at the age of 24 and has responded well to medication. Her family had no history of Parkinson's or other brain illnesses.
"As we understand more about genetics and the Human Genome, it's clear that a disease doesn't need to run in families to be genetic," says study author Andrew Singleton, a researcher at the Molecular Genetics Section of the Laboratory of Neurogenetics at the U.S. National Institute on Aging. "A recessive disease, which requires one faulty gene from each parent, can often appear in a patient without any affected relatives."
So far, the full meaning of the defective gene isn't clear. "What remains to be seen is if this mutation is a limited phenomenon, or does [it] play a more insidious role in other patients throughout the world," Tuite says.
Either way, more understanding of the gene in question could help scientists studying Parkinson's disease, he says. They could tinker with the genes of animals -- even a fly -- to give them forms of Parkinson's disease and study how treatments work, he says.
For now, there's no way to prevent Parkinson's. Once people get the disease, it's too late to turn back the brain damage, although medications can keep it from getting worse, Singleton says.
But determining that a patient is susceptible to the disease in the first place -- perhaps because of a defective gene -- could let doctors recommend preventative treatments before the disease appears, says Dr. Irene Litvan, director of the Movement Disorder Program at the University of Louisville. Those may include antioxidants, which have shown promise in research, or the simple avoidance of pesticides, she says.
More information
Learn about the symptoms of Parkinson's disease from the Parkinson's Disease Foundation or the National Parkinson Foundation.
