Which of the following statements about Wilson's disease is TRUE?

In Wilsons disease, due to deficiency of ATP7B protein, biliary copper excretion is impaired and it accumulates in the liver. Defective copper incorporation into ceruloplasmin leads to its excess catabolism and lower ceruloplasmin levels. Serum copper levels are usually lower than normal because of low blood ceruloplasmin. As the disease progresses, free copper levels increase and is deposited in various organs and is excreted in the urine. Ref: Harrison's principles of internal medicine 18th edition/ chapter 360.