As you maybe aware, Wilson's disease is an autosomal recessive disease, i.e. for it to be inherited the individual must have two abnormal genes (homozygous state), getting one each from both parents. In the presence of only one abnormal gene (heterozygous state), the individual becomes a carrier of Wilson’s disease without being affected by it. The carrier state is characterised by clinically mild abnormalities of copper metabolism. The gene responsible ATP7B (also called Wilson’s disease protein) is present on chromosome 13 and is usually inherited, though occasionally this mutation may arise spontaneously. The gene frequency in general population is estimated to be 0.3 to 0.7%. The ATP7B gene is found predominantly in liver, kidney, and placenta but also in the heart, brain, lung, muscle, and pancreas. The protein affected in Wilson disease transports copper in the liver cells, allowing for the incorporation of copper into ceruloplasmin and its subsequent excretion into the bile.
A large number of mutations (more than 200) have been described in the ATP7B gene so there is no simple screening test for the disease. If a precise mutation is identified in a particular family, analysis of parents and other relatives (called haplotype analysis) can help identify a symptom-free patient thus allowing early institution of therapy. Members in the same family who have the same genetic mutation in ATP7B may still have different phenotypes i.e. clinical expression of the disease.
A carrier can donate blood, as the gene cannot affect the recipient.