Wilson's disease (hepato-lenticular degeneration) is due to a deficiency of a substance called coeruloplasmin.
Coeruloplasmin carries copper in the blood. As a result, the level of copper cannot be maintained in the blood, excessive amounts are lost in the urine, and more important, are deposited in various organs, including the liver and the basal ganglia (lenticular nucleus). Several members of a family can be affected.
Severe involuntary movements develop in youth, and the patients become progressively more disabled, and deteriorate mentally.
Later they develop liver failure.
Copper is also deposited in the corneas of the eyes, producing a golden brown ring -- the Kayser-Fleischer ring.