Decode Locates the First Gene Linked to Late-Onset Parkinson's
By VANESSA FUHRMANS
Staff Reporter of THE WALL STREET JOURNAL
Decode Genetics Inc. said Tuesday it has mapped the location of a gene thought to be involved in late-onset Parkinson's disease, bolstering evidence that genetics play a key role in the most common form of the disease.
It's still too early to say when or if the development could lead to marketable medicine or tools to diagnose Parkinson's disease. But researchers say that, if substantiated, Decode's discovery could change the way scientists and doctors approach and hunt for new treatments for the disorder.
Researchers have linked some rare forms of Parkinson's disease to genetic factors. But whether the most common form, late-onset Parkinson's, is genetically linked remains disputed. One reason is that because this type of Parkinson's usually strikes people after the age of 50 -- not as children or young adults, as do most genetically linked diseases -- scientists have tended to believe environmental influences contribute to the disorder.
"For the great majority of people with Parkinson's, we just don't know the cause," said Dr. Abraham Lieberman, national medical director at the National Parkinson Foundation in Miami. "We usually say it's a combination of both [genetics and environment], but there's really no proof of either."
The Decode discovery, Dr. Lieberman says, is potentially "ground-breaking" in that it is the first to offer substantial evidence that Parkinson's can be traced back to genetic roots.
That could provide more clues to a cure. More than 10 million people world-wide are estimated to suffer from the degenerative neurological disorder, including 1.5 million Americans. Parkinson's leads to trembling and a progressive loss of control of motor functions.
Decode says it still hasn't identified the actual gene thought to be involved in Parkinson's, let alone a protein or some other target for which it could develop a drug. But Chief Executive Kari Stefansson says the Icelandic firm's scientists have pinpointed several candidate genes and are currently analyzing them for signs of mutation.
Dr. Stefansson said Decode first concluded there was a genetic link to late-onset Parkinson's after cross-referencing the complete genealogy of Iceland's population and tracking the disease through certain families. It detailed some of those findings in a study published in the New England Journal of Medicine in December 2000.
From there, scientists analyzed the DNA samples of volunteer Parkinson's patients and their unaffected relatives from 51 families across Iceland. Using that data, Dr. Stefansson says they were able to narrow down the location of the gene to a small region of chromosome 1.
Researchers caution that finding may not carry over to broader and more diverse populations, such as those in North America, and point out that genes related to other, rarer forms of Parkinson's, such as the parkin and alpha-synuclein genes, have largely been limited to isolated populations, too.
The discovery is one of the biggest developments so far in Decode's in-house drug-discovery program. Separately, in its $200 million (224 million euros) collaboration with Roche Holding AG, its discoveries include the identification of genes thought to be involved in schizophrenia, stroke and arterial disorders. |
