ATP7B protein deficiency impairs Biliary copper excretion resulting in positive copper balance Hepatic copper accumulation Copper toxicity from oxidant damage It leads to low serum ceruloplasmin due to excess catabolism of apoceruloplasmin. Low serum copper is due to low ceruloplasmin level. Non ceruloplasmin bound copper level will be high-free copper. Ref: Harrison, E-18, P-3188.