In Wilson disease (hepatolenticular degeneration), the primary molecular defect results in copper accumulation. Which protein is defective?

• A Ceruloplasmin — the serum copper transport protein
• B ATP7A — a P-type ATPase responsible for intestinal copper absorption
• C ATP7B — a hepatic P-type ATPase responsible for biliary copper excretion ✓
• D Metallothionein — the intracellular copper-binding protein

Explanation

Wilson disease is caused by mutations in ATP7B, a copper-transporting P-type ATPase expressed predominantly in hepatocytes. ATP7B normally incorporates copper into ceruloplasmin and exports excess copper into bile. Its deficiency leads to hepatic copper accumulation, decreased ceruloplasmin synthesis, and copper deposition in liver, brain (basal ganglia), cornea (Kayser-Fleischer rings), and kidneys. ATP7A deficiency causes Menkes disease (copper deficiency syndrome).

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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