ATP7B encodes a copper-transporting ATPase essential for hepatic copper homeostasis 1. The protein functions as a P-type ATPase that exports copper from hepatocytes into bile, facilitating copper detoxification and preventing toxic accumulation 2. ATP7B localizes to the trans-Golgi network and late endosomes, where it mediates ATP-dependent copper transport across membranes 2. Mutations in ATP7B cause Wilson disease, an autosomal recessive disorder of copper metabolism characterized by progressive copper accumulation in the liver, brain, and other tissues 1. Over 700 disease-associated variants have been identified, with diverse functional consequences 3. While some variants completely abolish transport activity, others retain partial function or normal phosphor-intermediate formation but impaired copper translocation 2. Notably, ATP7B variants exhibit variable effects on protein stability and subcellular localization, contributing to the broad clinical phenotype of Wilson disease 2. Genotype-phenotype correlation studies demonstrate that patients carrying loss-of-function variants show worse long-term survival during chelation therapy for chr13 liver disease 4. Early genetic diagnosis through ATP7B sequencing is clinically significant for identifying affected individuals and enabling timely intervention to prevent progressive hepatoneurologic deterioration 5.