Modifier of copper toxicosis, ATP7A-related

Copper levels in the body are regulated by copper intake from food and by copper secretion from certain parts of the body (the bile ducts). Two proteins, ATP7A and ATP7B, are responsible to maintain normal copper levels in the body. ATP7A is expressed in intestinal cells and transports copper to the liver where it is stored whereas ATP7B is expressed in liver cells but also in brain cells and secretes the copper into the bile ducts. A mutation in the ATP7A gene leads to a copper deficiency in the body which is called Menkes disease. In addition, a mutation in the ATP7B gene leads to copper accumulation in the body which is called Wilson disease.

Labrador Retrievers with mutations in both genes can have varied copper levels depending upon the combination of the alleles and environmetal factors. Literature suggests that these combinations can have an attenuated effect on copper level changes in the body. This means that dogs with these genotypes will likely be unaffected.