Researchers find brain calcifications do not relate to development of dystonia symptoms

Friday, August 18, 2006

JACKSONVILLE, Fla. — By studying a large family with many individuals diagnosed with dystonia, a group of researchers, led by Mayo Clinic neurologist Dr. Zbigniew Wszolek, M.D., determined that the presence of calcium deposits in the brain alone is not entirely responsible for the disease. Wszolek and his colleagues will publish their findings in the Aug. 22 edition of the journal Neurology.

Although calcium accumulation in the brain is associated with more than 50 clinical conditions, calcium deposits had not been associated with dystonia until they were found in members of a large Canadian family, many with the disease. Dystonia is a neurological disorder that causes involuntary, sustained muscle contractions, which result in repetitive movements, twisting and abnormal postures.

Some researchers thought the presence of calcium deposits in the brain might be a predictor of who might develop dystonia. Wszolek and his colleagues did not find that to be true.

In family members who underwent CT scans of the head, there was no difference in the extent and severity of brain calcifications between individuals with dystonia and those exhibiting no dystonia symptoms. Some individuals had severe brain calcifications in one or more regions of the brain but lacked dystonia symptoms.

Equally puzzling was the fact that in some individuals with dystonia, researchers found mild calcification in few regions of the brain; in others, they found severe calcifications in many brain regions. "In this particular family it appears brain calcifications and dystonia are linked," Wszolek says, "but what is interesting is the amount of calcification did not necessarily reflect the severity of dystonia."

Based on the specific presentation of the disease in this family, researchers performed sophisticated genetic screenings for the presence of a suspect gene in three different genetic regions known to contain a disease-causing dystonia gene. They found none. "I think there may be another gene," Wszolek says. "So we hope to find the gene, and by knowing the gene, we hope to learn more about the disease. Hopefully this will lead to more basic studies and eventual treatments."

While calcium may accumulate in the brain independent of the dystonia disease course, brain calcifications themselves appear to cause no clinical symptoms.

Collaborators and Support
The Mayo Clinic research team also included: Yasuhiko Baba, M.D. and Yohshi Tsuboi, M.D. (now at Fukuoka University School of Medicine, Fukuoka, Japan); Matthew Baker; Daniel Broderick, M.D.; Michael Hutton, Ph.D.; Stacey Melquist, Ph.D.; Audrey Strongosky; and Ryan Uitti, M.D. From the University of British Columbia, Vancouver, Canada: Ian Mackenzie, M.D.; Patrick McGreer, M.D.; and Judit Miklossy, M.D. From the Eastern Ontario Regional Genetics Program, Children's Hospital of Eastern Ontario, Ontario, Canada: Judith Allanson, M.D. From the Pacific Parkinson's Research Centre: Donald Calne, D.M.A.; Susan Calne; Jonathan Carr, M.D. (now at the University of Stellenbosch, Tygerberg, South Africa); Ajit Kumar, M.D.; and Jon Stoessel, M.D.

This work was supported in part by: the National Institute of Neurological Disorders and Stroke/Udall Center of Excellence for Parkinson's Disease Research; the Dystonia Medical Research Foundation; the Canadian Institutes of Health Research; the Pacific Parkinson's Research Institute; a Canada Research Chair; and the Robert H. and Clarice Smith Fellows program.

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