Copper metabolic defects and liver disease: environmental aspects

Abstract

Copper (Cu) is an essential trace element for many biological processes. Cu homeostasis is generally well maintained by inbuilt controls in intestinal absorption, biliary excretion and intrahepatic storage. Copper deficiency disorders are rare. Acute Cu toxicity occurs occasionally in accidental poisoning with Cu sulfate. Chronic Cu toxicity in the form of liver cirrhosis and damage to other organs is seen classically in Wilson's Disease (genetic abnormality of Cu metabolism) and in the presumed environmental disorder Indian Childhood Cirrhosis (ICC). The clinical, epidemiological and treatment aspects of ICC are described. The evidence linking ICC to environmental Cu is (i) greatly increased hepatic Cu; (ii) early introduction of Cu contaminated milk boiled or stored in brass vessels; (iii) dramatic decline in ICC throughout the country coincident with change in feeding vessels; and (iv) continued long-term remission in d-penicillamine-treated patients after withdrawal of the drug. The nature and role of a second factor in the causation of ICC remains unclear, although a genetic predisposition is strongly suspected. Scattered reports of an ICC-like illness from the West (Idiopathic Cu Toxicosis, Endemic Tyrolean Infantile Cirrhosis), suggest that different mechanisms (environmental, genetic or both) can lead to the same end stage liver disease-'ecogenetic' disorders.