Wilson disease is an autosomal recessive disease, which means it occurs equally in men and women. In order to inherit Wilson disease, both parents must carry one genetic mutation (abnormal alteration in the gene) that each parent passes to the affected child. At least one in 30,000 people of all known races and nationalities has the disease. Of the 23 different human chromosomes, the gene responsible for Wilson disease is located on chromosome 13. The gene is called ATP7B and it contains the genetic information necessary to make a copper transport protein that plays a key role in incorporating copper into ceruloplasmin and moving excess copper out of the liver. Mutations in the gene lead to an abnormal copper transporter that cannot move copper effectively or at all. More than 300 genes of the ATB7B have been identified thus far.This excess copper accumulates in the liver and other organs. Most patients have no family history of Wilson disease. People with only one abnormal gene are called carriers. Carriers (heterozygotes) may have mild, but medically insignificant, abnormalities of copper metabolism. Carriers do not become ill and should not be treated. Wilson disease patients (homozygotes) do become ill and must receive treatment lifelong or eventually they will develop severe lethal disease.One in 100 individuals in the general population carries one abnormal copy of the Wilson disease gene. Carriers have one normal and one abnormal gene. All (100%) children of those afflicted with Wilson disease receive at least one abnormal copy of the Wilson disease gene. One half (50%) of a carrier’s children receive at least one abnormal copy of the Wilson disease gene. A genetic counselor can provide a more detailed pedigree of specific family relationships.