Gene Predicts Parkinson's Progression

The finding may help explain why some patients deteriorate faster than others.

ByABC News
May 15, 2012, 6:35 PM

May 16, 2012— -- Diane Cook's 65th birthday was a milestone for her, but not because of her age. That was the day she was diagnosed with Parkinson's disease.

"I was stunned," she said, adding that even though she had had symptoms for four years before being diagnosed, the news was still a surprise.

That day, she could not muster the courage to learn more about what was in store for her. But the next day she pored over the Internet to learn about the disease. She quickly discovered that it would continue to get worse, and that there was no cure.

Parkinson's disease, often associated with boxer Muhammad Ali and actor Michael J. Fox, affects 1 million Americans, according to the National Parkinson Foundation.

While the exact causes largely remain a mystery, doctors know that the condition arises from the degeneration of a specific area of the brain involved in movement. As a result, those with Parkinson's experience tremors, rigidity, slowness in moving, and difficulty with balancing and walking.

Parkinson's eventually leads to mood disorders and dementia. The complications associated with the condition are the 14th largest cause of death in the United States, according to the U.S. Centers for Disease Control and Prevention.

Not only is there no cure for Parkinson's, but many patients have no way of knowing how quickly their symptoms will progress.

"We all worry about how rapidly we'll lose our abilities," Cook said. "The uncertainty is very frustrating."

A new study from UCLA may help. Researchers have found two variants on a gene already known to be associated with Parkinson's that may be able to predict how quickly patients with the condition will deteriorate. The study found that patients with one particular variant were four times as likely to have rapid decline of motor function. Those patients having both of the variants studied were even more likely to see their disease progress more quickly.

The information is important, as patients who have more severe motor disease tend to die sooner.

Dr. Beate Ritz, vice chair of epidemiology at UCLA and the neurologist who conducted the study, stated that up to now, there has been no way to gather this information from a patient's genes. Finding the telltale signs of a faster decline, she said, helps doctors in "identifying patients who will most benefit from early interventions."

Ritz's study observed 233 patients in California for an average of more than five years -- making it the largest study of its kind on Parkinson's disease motor symptoms to date.

"The strength of this study is that is uses a population-based approach," said Gary Miller, professor at Emory University's Rollins School of Public Health. Miller explained that most studies are based out of specialty centers, rather than looking at patients in the community at large as this study did.

Dr. Puneet Opal, an expert in movement disorders at Northwestern University's Feinberg School of Medicine, said the study poses an interesting idea, at least in terms of the basic mechanism of the disease. However, he said he doesn't believe it will change the management of Parkinson's patients very much.

"If I knew that my patient had one of these genetic variants, I wouldn't treat him any differently than my other Parkinson's patients," he said. The next step, he said, would be to figure out exactly how the brain is damaged by Parkinson's disease.

This research does not go that far -- nor does it offer a new treatment approach for patients like Cook, who has now lived with the disease for four years. But despite this, she said she feels the research is still useful. As a Parkinson's Disease Foundation research advocate, she said she has noticed that when patients volunteer for studies, their attitudes change.

"They no longer feel like victims," she says, adding that the ability to actively participate in advancing the knowledge of Parkinson's disease is therapy in and of itself.

Cook herself has participated in seven different research trials. She continues to be proactive about her disease and also educates newly diagnosed patients through two support groups she runs.

"Parkinson's is the best worst thing that ever happened to me," she said.