A 19-year-old woman is bothered by a tremor at rest, which becomes progressively worse over the next 6 months. She exhibits paranoid ideation with auditory hallucinations and is diagnosed with acute psychosis. On physical examination, she has scleral icterus. A slit-lamp examination shows corneal Kayser-Fleischer rings. Laboratory findings include total serum protein, 5.9 g/dL; albumin, 3.1 g/dL; total bilirubin, 4.9 mg/dL; direct bilirubin, 3.1 mg/dL; AST, 128 U/L; ALT, 157 U/L; and alkaline phosphatase, 56 U/L. Which of the following additional serologic test findings is most likely to be reported in this patient?

Wilson disease is an inherited disorder in which toxic levels of copper accumulate in tissues, particularly the brain, eye, and liver. The ATP7B gene for Wilson disease encodes a copper-transporting ATPase in the hepatocytes. With mutations in this gene, copper cannot be secreted into plasma. Ceruloplasmin is an a2 -globulin that carries copper in plasma. Because copper cannot be secreted into plasma, ceruloplasmin levels are low. Chronic liver disease and panlobular emphysema may occur in a1 -antitrypsin deficiency. An increased a-fetoprotein is a marker for hepatocellular carcinoma. Increased serum ferritin may indicate hereditary hemochromatosis. A positive finding for antimitochondrial antibody can be seen in primary biliary cirrhosis. A positive HBsAg result indicates HBV, which infects only the liver.