March 30, 1996
New liver disease caused by excess zinc, copper, SickKids study shows
TORONTO - A new liver disease caused by excessive amounts of zinc and copper has been identifed by pathologist James Phillips and colleagues at The Hospital for Sick Children, it was announced in today's issue of the British scientific publication Lancet.
The condition was discovered when they found abnormally dense deposits of copper and zinc in livers removed at transplantation. Although there are several diseases in which high levels of copper are found in the liver, there is no known disease in which the liver contains high zinc concentrations.
"We believe there is a strong association between this severe chronic liver disease that ultimately causes the organ to cease functioning, and the presence of zinc and copper in the livers of the children we studied," Dr. Phillips explains. "What we don't know is if it's due to zinc and copper together or zinc alone.
"The excess copper may be due to stoppage of bile excretions over an extended period," he says, "but the excess zinc is unexplained. Since three of the patients are related, a genetic disorder of metal metabolism is considered likely. At the same time, we cannot exclude environmental factors such as the water supply or the food chain."
Zinc concentrations more than 40 times higher than normal and copper concentrations ten times higher than normal were found through cryo-analytical electron microscopy of the dense deposits in the liver cells and atomic absorption spectrophotometry of liver samples from six Native Canadian children, aged 22 months to eight years. One patient in the research study is Cree from land bordering Hudson Bay; four are Ojibwa-Cree from the Algoma Region. Three have common grandparents. The children were referred to The Hospital for Sick Children because of end-stage liver disease. Liver transplants have subsequently been performed on five.
"One to two years after transplanation, liver biopsies are showing low levels of reaccumulation of zinc and copper in the lysosomes of the liver," Phillips said. "This leads us to wonder if this is a progressive disease."
Dr. Phillips is a professor in the Department of Pathology and Medical Biochemistry, Faculty of Medicine, University of Toronto. The Hospital for Sick Children is a health care, teaching and research centre dedicated exclusively to children affiliated with the University of Toronto.
For more information, please contact:
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