What disease causes copper toxicity?

• A. Menkes disease
• B. Klinefelter syndrome
• C. Hemochromatosis
• D. Wilson's disease

Answer: (D)

Copper overload from impaired excretion is seen in Wilson's disease, where a mutation in the ATP7B gene disrupts the body's main disposal route for copper. This defect prevents copper from being excreted into bile and hinders its incorporation into ceruloplasmin, allowing copper to accumulate in the liver first and then in other organs such as the brain and cornea. The result is potential liver dysfunction or neuropsychiatric symptoms, and a classic sign is Kayser-Fleischer rings in the cornea. Laboratory clues include low ceruloplasmin levels and elevated urinary copper, with hepatic copper content sometimes used for confirmation. Treatment focuses on chelation to remove copper (for example, penicillamine or trientine) and zinc to reduce intestinal copper absorption. The other conditions listed do not cause copper toxicity: Menkes disease leads to copper deficiency; hemochromatosis involves iron overload; Klinefelter syndrome is unrelated to copper metabolism.