So far, five spinocerebellar ataxia (SCA) genes have been identified. The ataxia caused by the SCA 10 gene localized by the Cedars-Sinai team is different from the other ataxias. One of these, the occurrence of seizures in 20 percent of family members suffering from the disease, indicates a possible link with epilepsy. Further study of the new gene is expected to shed new light not only on ataxia, a relatively rare inherited disease that affects one in 10,000 persons, but also on the pathogenesis of epilepsy, a condition that affects one in 100.
LOS ANGELES -- Neurogeneticists at Cedars-Sinai Medical Center in Los Angeles have localized SCA10, a gene involved with a rare form of inherited ataxia, a disease whose onset usually comes in early adulthood and that causes incoordination of gait and movement. The finding is reported in the February issue of the American Journal of Human Genetics.
Five spinocerebellar ataxia (SCA) genes had been previously identified by various research groups, including SCA2, which, like SCA10, was found by the Cedars-Sinai team of Stefan-M. Pulst, M.D. Like SCA2, SCA 10 shows anticipation, a phenomenon whereby onset of the disease is earlier and earlier with each successive generation. The presence of anticipation may provide an important clue for the isolation of the gene, since it may indicate that the genetic defect is caused by unstable DNA repeats.
In contrast to other inherited ataxias, however, 20 percent of members of the family affected by the ataxia suffered seizures. "This connection makes isolation of the genetic defect so exciting", says Dr. Pulst, "because it will likely shed light on the much more common epilepsies."
It was approximately a year ago that the Pulst team identified the
Mexican-American family exhibiting the rare form of ataxia. They have now been
able to localize the SCA10 gene on the long arm of chromosome 22 by conducting a
search that included some 300 genetic
Contact: Sandra Van
Cedars-Sinai Medical Center