Excess zinc associated with severe progressive cholestasis in Cree and Ojibwa-Cree children

Background. High hepatic copper concentrations have been reported in several liver disorders. We report six Native Canadian children with severe chronic cholestatic liver disease, who had excess hepatic copper and zinc. Methods. The children, aged 22 months to 8 years, came from northern Ontario, Canada. All were referred for possible liver transplantation because of end-stage liver disease. We examined explanted liver samples (or liver biopsy material in one case) by scanning transmission electronmicroscopic (STEM) X-ray elemental microanalysis and atomic absorption spectrophotometry. Samples from four controls (two with no liver pathology, one with biliary atresia, and one with Wilson's disease) were also analysed by atomic absorption spectrophotometry. Findings. The explanted livers showed similar distinctive signs of advanced biliary cirrhosis, and on electronmicroscopy there were dense deposits in enlarged lysosomes and in cytoplasm. Hepatic copper concentrations were many times higher in the five patients with measurements (47.6-56.9 μg/g dry weight) than in two samples of normal control liver tissue (2.3 and 2.9 μg/g). Similarly, hepatic zinc concentrations were many times higher in the patients than in controls (104-128 vs 1.9-3.2 μg/g dry weight). Interpretation. The excess copper may be due to chronic cholestasis but the excess zinc is unexplained. Since three of the patients are related (shared grandparents), a genetic disorder of metal metabolism is possible, but we cannot exclude environmental factors.