Company Press Release
SOURCE: Mayo Clinic Jacksonville
Mayo Clinic Jacksonville Researchers Discover
Area Of Chromosome That Probably Contains
The Cause Of Parkinson's Disease
JACKSONVILLE, Fla., Dec. 17, 1998 /PRNewswire/ -- Researchers at Mayo
Clinic Jacksonville have discovered an area
of chromosome that probably contains a genetic mutation that causes
Parkinson's disease within families. The team has
also found evidence in six generations of an Iowa family that
Parkinson's disease and essential tremor, by far the most
common of movement disorders, may be caused by the same mutation. This
finding could change the way neurologists
approach both illnesses.
``There are millions of Americans suffering from either Parkinson's or
essential tremor, and this research brings us one
step closer to finding the cause for their diseases,'' says Dr. Katrina
Gwinn-Hardy, a neurologist on the Mayo
Jacksonville research team.
In an article scheduled for the January 1999 issue of Human Molecular
Genetics, Mayo researchers describe how they
have narrowed down the genetic mutation that may cause Parkinson's
within families to a portion of the chromosome
``4p''. In the Iowa family, that part of chromosome 4p occurs only in
members who have either Parkinson's or essential
tremor. By testing the DNA in the blood of this large Iowa-based family
with a history of Parkinson's over six known
generations, the researchers have been able to localize the affected
area of the chromosome, but they have not yet been
able to identify the specific gene.
``This is a breakthrough in the search for the cause and possible cure
one day for Parkinson's disease,'' says Matt
Farrer, Ph.D., molecular researcher and leader of the research team at
Mayo Clinic Jacksonville. ``By looking at the
pattern of the disease within the family and their genetic material from
blood samples, we've been working to determine
what bits of genetic material the affected siblings share that the
unaffected ones do not.''
Scientists have previously located one genetic mutation for Parkinson's
located in a different location on chromosome 4,
as well as one localized to chromosome 2, but the mutation on chromosome
4p is unique to members of the ``Iowa
kindred''. This is the first time that essential tremor and Parkinson's
disease have been shown to be genetically linked.
``To identify the actual gene responsible for the disease, we need to
find other affected individuals and families,'' says
Gwinn-Hardy. ``Once the gene is found, we can develop models to study
the problem and then determine what
interventions might be useful in slowing or preventing the disease.''
Parkinson's disease causes tremor when the limb is at rest, in addition
to causing rigidity in limbs and joints, and difficulty
with balance and walking. Essential tremor is a disorder characterized
by a mild tremor in the hands and arms that
occurs in any activity such as writing or holding a cup. Affected
individuals respond differently to medications depending
on which of the two diseases they have, and people with essential tremor
usually do not develop Parkinson's.
The Mayo research team is looking for families in the United States who
have three or more members with Parkinson's
disease as well as those with early onset of Parkinson's (under 50
years). These people are asked to contact the team at
Mayo Clinic Jacksonville for more information by calling 904-953-2439 or
through e-mail: [log in to unmask]
At this time, the Iowa family is providing a wealth of information for
researchers trying to determine the cause of
Parkinson's. Each of the six known generations of the family has at
least one member with Parkinson's. The average age
of onset has been 34. Some members of the family have been treated at
Mayo Clinic in Rochester, Minn. since the
1930s. Using a molecular genetic technique known as ``positional
cloning,'' scientists have extracted the DNA from the
blood of many family members, copied it hundreds of times and identified
a chromosomal region which has been
inherited by people affected by Parkinson's disease and predisposed them
to movement disorder.
SOURCE: Mayo Clinic Jacksonville
--
Judith Richards, London, Ontario, Canada
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