According to a report to be released in the October 1 issue of Nature Genetics, researchers at Baylor College of Medicine (Houston, TX) and at Cedars-Sinai Medical Center (Los Angeles, CA) have identified the gene on chromosome 22 and the causative mutation that is linked to inherited diseases that lead to motor incoordination and epilepsy. Known as Spinocerebellar Ataxia Type 10 (SCA10), this finding is significant in that epilepsy is not typically associated with late-onset ataxias.
Ataxia is an umbrella description of neurodegenerative disorders that cause such disabling symptoms as unsteadiness and an inability to coordinate muscle movements. More than 150,000 Americans suffer from ataxias.
METHODOLOGY: According to Stefan-M. Pulst, M.D., Director of the Division of Neurology at Cedars-Sinai Medical Center who holds the Carmen and Louis Warschaw Chair in Neurology, researchers in the two-and-one-half year study extracted DNA from blood samples of the participating members of five SCA10 families, then combed through the DNA sequences looking for DNA repeats on chromosome 22. At the same time, they focused on clinical data indicating that this type of ataxia tends to strike earlier and earlier in subsequent generations. In the SCA10 families studied, all of which were of Mexican ancestry, the researchers found that in all patients a DNA repeat of five bases was repeated hundreds of times more than in normal individuals. Further, they found an inverse correlation between the expansion size and the age of disease onset.
RAMIFICATIONS: Identification of this gene mutation, may lead to pre-symptomatic diagnoses, and earlier treatment. “Ultimately,” says Dr. Pulst, “there is the possibility that over the next decade, we may be able to identify ways to prevent the death of neurons and thus develop preventative measures for this type of disorder.”
LEAD INVESTIGATORS: Tetsuo Ashizawa, M.D., Professor of Neurology, Baylor College of Medicine Stefan-M. Pulst, M.D., Director of the Division of Neurology at Cedars-Sinai Medical Center; and holder of the Carmen and Louis Warschaw Chair in Neurology
FUNDING: Funding for this research was provided by the National Institutes of Health and by the National Ataxia Foundation.
OTHER: Researchers at Cedars-Sinai Medical Center have previously discovered and localized genes involved in neurodegenerative disorders. The September, 2000, issue of Nature Genetics published the results of a study in which the scientists analyzed biologic, chemical and genetic mechanisms in an attempt to discover how mutation in the SCA2 gene actually causes damaged nerve cells. Earlier, Dr. Pulst was one of the lead scientists in the 1996 discovery of the spinocerebellar ataxia type 2 (SCA2) gene. The teams of Drs. Pulst and Dr. Ashizawa had independently identified the location of the gene for SCA10 on chromosome 22 last year.
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Materials provided by Cedars-Sinai Medical Center. Note: Content may be edited for style and length.
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