ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Friday, November 15, 1996 TAG: 9611150064
SECTION: NATIONAL/INTERNATIONAL PAGE: A-4 EDITION: METRO
DATELINE: WASHINGTON
SOURCE: The Washington Post
Scientists have found the approximate location of a gene that causes an inherited form of Parkinson's disease, an accomplishment they say could someday lead to new treatments for the incurable brain disease.
The work offers the strongest evidence yet that genetic factors can play a role in the mysterious and potentially fatal disease, which is characterized by tremors, muscle rigidity and a gradual loss of mobility. Although doctors have long known Parkinson's is more common in some families than others, they have never been able to resolve whether it is primarily inherited or caused by environmental factors.
The new research, described in today's issue of the journal Science, shows Parkinson's is almost entirely genetic in at least one heavily studied family with a history of Parkinson's dating back to the 18th century. About 85 percent of those people who inherited a defect on chromosome 4 came down with the disease, researchers found.
``This is the first solid evidence for any genetic cause for Parkinson's disease,'' said Mihael Polymeropoulos, a geneticist at the National Center for Human Genome Research who is the study's principal investigator.
Researchers emphasized the exact identity of the defective gene - and most important, its function - could take a year or more to find. It is still not known whether the gene plays a role in the far more common ``sporadic'' cases without an apparent hereditary pattern, or even in other families with Parkinson's clusters.
``What patients should not take home from this is that we have found a new form of diagnosis for Parkinson's, a new form of therapy, or a new form of prevention,'' said National Institutes of Health Director Harold Varmus.
Nonetheless, Varmus and others said, the finding could spur the development of all those things, even if most cases are caused by something else.
``It may be that even if this family is the only one affected [by this gene], what we find out from it may tell us something that is useful for treating all other cases,'' said Zach Hall, director of the National Institute for Neurological Disorders and Stroke, which helped pay for the work. Ultimately, scientists said, it may turn out that Parkinson's can be caused by one or more genetic mutations, sometimes in conjunction with exposure to a toxin or infectious agent.
Parkinson's is characterized by a deterioration of a type of brain cell that normally produces a chemical messenger called dopamine. As dopamine supplies dwindle, the brain loses its ability to coordinate muscle movements.
About 1 million Americans have the disease. It costs the nation an estimated $6 billion a year in health care expenses and lost productivity.
One drug, levodopa or L-dopa, reduces symptoms, but eventually loses its potency. Surgical interventions remain controversial and unproved.
Scientists' efforts to develop better treatments have been hindered by a failure to understand why the dopamine-producing cells die. The new work sought to answer that question by finding a gene that, when disabled, can cause Parkinson's.
LENGTH: Medium: 61 linesby CNB