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Monday March 2 1:06 PM EST=20

Suspected Parkinson's Gene Located

NEW YORK (Reuters) -- Scientists have located a gene shared by a group =
of families with a predisposition to Parkinson's disease, according to a =
report in Nature Genetics.=20

The genetic mutation, located on chromosome 2, "appears to be involved =
in the development of parkinsonism closely resembling sporadic (typical) =
Parkinson's disease," according to researchers led by Dr. Thomas Gasser =
of Ludwig-Maximilians-Universitat in Munchen, Germany.=20

Parkinson's disease is a chronic neurological illness which causes =
tremors, loss of facial expression, and a gradual deterioration in =
muscle control.=20

The German discovery follows a recent announcement that a =
Parkinsons-linked gene discovered earlier this year among the members of =
one Italian family might not, after all, be linked to the most typical =
and widespread form of the disease. As reported by Reuters on February =
25th, a study led by Dr. J. William Langston of the Parkinson's =
Institute in Sunnyvale, California, failed to find the gene in the DNA =
of 100 Parkinson's patients. Langston believes the gene carried by the =
Italian family is "not common in the general population."=20

However, the German researchers believe the mutation they have located =
may be more likely to play a role in the development of Parkinson's. =
They note that the gene is shared by seven different north-European =
families, and produces at least "four cardinal signs of (typical) =
Parkinson's disease," including disease onset at a typically late age =
(around 60 years). Affected family members also respond well to =
treatment with the neurotransmitter L-dopa; a response similar to that =
of patients suffering from the most common form of Parkinsons.=20

The investigators describe the gene as "autosomal dominant," meaning =
that a child need only receive the gene from one parent to run the risk =
of developing Parkinson's in later life. Still, the researchers note =
that only 40% of family members who carry the gene go on to develop the =
disease. They believe that "other genetic or non-genetic factors =
(besides the presence of the 2p13 gene) may determine severity of (gene) =
expression."=20

The researchers believe a common mutation, occurring in the distant =
past, may link at least two of the affected families. "The ancestors of =
both families... originate from neighbouring regions of southern Denmark =
and northern Germany," explain the study authors. "In view of the close =
historical ties between these regions, a common ancestry seems possible. =
This finding may thus point to the presence of a founder mutation which =
might also be present in additional Parkinson's disease cases from this =
area." SOURCE: Nature Genetics (1998;18:262-265)