NEW YORK (Reuters Health) - Researchers have evidence that a missense mutation in HS1-BP3, a gene that plays an important role in dopamine metabolism, may be involved in familial essential tremor.
“The presence of this gene mutation in familial essential tremor provides a genetic tool to refine the diagnosis and help distinguish essential tremor from Parkinson’s disease,” Dr. Joseph J. Higgins, director of the Center for Human Genetics and Child Neurology at the Mid-Hudson Family Health Institute in New Paltz, New York, who led the effort, told Reuters Health.
The identification of this gene will also increase our understanding of the causes of essential tremor and facilitate research on the treatment of tremor, he added.
“Genetic factors undoubtedly play a major role in essential tremor since most cases are dominantly inherited and there is a high concordance rate among monozygotic twins,” Dr. Higgins explained.
Previous genetic linkage studies have pinpointed two susceptibility loci for essential tremor -- one on chromosome 2p24.1 and the other on chromosome 3q13 -- in several families affected by essential tremor in different parts of the world.
Dr. Higgins’ group conducted detailed mapping studies of families with essential tremor genetically linked to chromosome 2p24.1 and found an 828C to G missense mutation in the HS1-BP3 gene in two apparently unrelated families.
Altogether, this variant was associated with essential tremor in about 10% of the 21 U.S. families analyzed, but was not found in 73 Singaporean individuals with essential tremor or in any of 150 U.S. controls with no history of essential tremor, they report in the February 8th issue of Neurology.
HS1-BP3 is a “logical candidate for causing tremor because it is involved in regulating dopamine metabolism in the brain,” Dr. Higgins said. “This genetic variant will permit better identification of essential tremor in as many as 10% to 15% of cases.”
“It will also help distinguish between essential tremor and Parkinson’s disease during early stages,” he added, noting also that misdiagnosis of essential tremor is a problem because there is no definitive test. “This lack of diagnostic accuracy leads doctors to treat individuals with essential tremor for Parkinson’s disease,” the researcher said.
Source: Neurology 2005;64:417-421. [ Google search on this article ]
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